To many, the contents of this conference may not seem appropriate at a time when the minds are preoccupied with a "population explosion." To the participants and guests of this conference, however, this was a week of fascinating discussions. While quantitative aspects of reproduc tion were touched upon, it was mostly a search for an understanding of the qualitative aspects of reproduction and its failure. Only when we understand these more completely will it be possible to render optimum care and have the foundations for meaningful population control. The conference was conceived in discussions at the Committee on Pathology of the National Academy of Sciences, W"ashington, in 1965. It was felt that investigators in medicine and the veterinary fields would profit greatly from a closer liaison. All too frequently, we work relatively isolated in our respective fields and, with the burgeoning information filling our journals, we have not enough time and leisure to stand back and attempt a comparative look at the subject of study. Often we are not familiar with the techniques other disciplines use, and which we could well employ to great advantage., yhile this applies to many aspects of medicine, a comparative approach to the study of reproductive failure seemed most advantageous at this time."

The patriarch of experimental pancreas research is REIGNIER DE GRAAF (1641-1673). He carried out the first experiments with dogs in order to ob tain fistular secretion (1664). But only few years later, the just arisen interest in the physiology of the pancreas was severely set back by remarks of CONRAD BRUNNER. In 1682, BRUNNER expressed his belief that on the basis of experi ments he had carried out the pancreas was a vitally unimportant organ. He overlooked that after ligation of the main duct (discovered in the turkey by HOFMAN in 1641 and in a human cadaver by WIRSUNG in 1642), in the dog an accessory duct (described by SANTORINI in 1724) usually maintains an adequate flow of secretion. EBERLE in his monograph (1834) confirmed the emulsifying capacity of the pancreatic juice which had already been suggested by SYLVIUS (FRAN CISCUS DE LE BOE, 1614-1672) and he dealt with the essential enzymatic functions of the pancreatic juice such as amylolysis, lipolysis and proteolysis. Since HEIDENHAIN (1875), we know that for example trypsin (largely isolated by KUHNE in 1867) is situated in the acinar epithelial cells as zymogen in inactive form; it is thought that the action of "acid" on the glandular tissue is needed for inducing the "enzymatic activity." According to what we know now about the central role of acidosis in the activation of zymogen this topic is, of course, of topical interest."

The last decade has seen remarkable advances in human ge netics. Once the correct chromosome number of the human genome was ascertained, a wide variety of diseases was rec ognized as due to numerical chromosome anomalies. There followed the discovery that spontaneous abortions are the result of chromosome errors, and specific band patterns of chromosomes allowed identification of minute lesions. The techniques of cell hybridization now allow specific gene assign ment to chromosomes and even to distinct loci on their arms. All this was possible because of the ease with which metaphase chromosomes can be obtained and manipulated. The much older technique of analysis of meiotic chromosomes has taken a back seat in this exciting era. Being much less readily accessi ble, spermatogonial analysis is much less frequently under taken and is less successful. Even more difficult for study is the female meiotic process. Not only is meiosis extraordinar ily long, spanning from before birth to ovulation, the tech niques for its study and the patience required for detailed inquiry have been significant obstacles. At the same time, the suspicion that female meiotic analysis should not only be rewarding but that it may be mandatory has been with us ever since it was recognized that a positive correlation exists between chromosomal nondisjunction and maternal age. Before the intricacies of chromosomal behavior that are re sponsible for nondisjunction are understood, however, it is necessary that we comprehend the normalcy of the process."

Toxoplasmosis is a ubiquitous infection, contracted by at least a third of the population in most areas of the globe. Clinical disease arises rarely, usually unexpectedly, but sometimes with disastrous effects on the patient. Humans, pets, farm and zoo animals may contract toxoplasmosis, possibly involving any clinical laboratory in its diagnosis. Pathologists must ponder the clinical significance of a hyperplastic l. ymph node, a cyst found at autopsy, or a serologic titer. Serving as scientific physicians, pathologists are asked: How is toxoplasmosis diagnosed? 'What is the treatment for ocular toxoplasmosis, for congenital infection, or for toxoplasmosis in the immunologically compromised host? vVhy does disease develop in as diverse areas as the eye, lymph nodes and placenta? How is Toxoplasma transmitted? This review proposes to survey recent advances, providing a scientific background to diagnose and manage the clinical problems of toxoplasmosis. Reviews are available which emphasize other aspects, such as serologic pro cedures, resistance and immunity (REMINGTON, 1970), the clinical syndromes (DESMONTS, '1969; FELDMAN, 1968) and comprehensive presentations (JACOBS, 1967; FRENI{EL, '1970). Transmission and Prevalence The recent discovery of the coccidian stages of Toxoplasma in the cat intestine and the Toxoplasma oocyst excreted in cat feces, considerably broadens our understanding of Toxoplasma and its transmission (FRENKEL, DUBEY and MILLER, 1970)."