234 PROCEEDINGS OP THE ACADEMY OF [1896. 



letin, Uuiv. of Penna., 1889. Extensions of opinion were printed 

 in tlie Proceedings of the Academy, 1889, and in the American 

 Naturalist, 1889, 501. He held that over-nutrition led to all forms 

 of sexual reproduction ; that the male and female elements are con- 

 trasted in their tendency to undergo segmentation — the female ele- 

 ment having lost the power to undergo such segmentation spontane- 

 ously (excepting in parthenogenesis), — while the male element is 

 accompanied by an increase of segmental power, -^ ^ -^ ^ 

 " Sex probably arose simultaneously and independently in both 

 female and male as soon as certain cells of coherent groups became 

 over nourished, and incapable of further segmentation unless 

 brought into contact and fused with the minute male element, or 

 one which is the product of an increase of segmentational power 

 which is transferred to the female element in the act of fertilization." 

 Important applications were made of the hypothesis to the study of 

 variation, the evolution of sexual characters, and, as the author be- 

 lieved, a consistent and simple theory of inheritance which is in 

 harmony with all the facts of reproduction. At this time he was in 

 a state bordering on exaltation. " I sat up late last night after the 

 whole thing flashed across my mind in an instant," he writes, " and 

 did not sleep for two hours after I went to bed because my brain 

 was going like a dynamo, thinking out detail after detail of my hy- 

 pothesis. * * * * Wolfe and Schwann mark two eras in the 

 history of hypothesis. I shall mark a third if I live to complete 

 the sketch of the vast hypothesis. * * * * My disappoint- 

 ments vanish into the uttermost inane when I think of what it has 

 been possible for me to achieve." 



After such strong evidence of his belief in the value of this theory, 

 it is hard to understand how he practically dropped the subject. 

 Subsequent to the dates above given, I have come across no refer- 

 ence to it, nor is any mention made of the matter in the estimates 

 of his work that have appeared since his death. 



It is impossible to understand Ryder's attitude toward evolution, 

 without regarding his disbelief in the " cult " usually known as Weis- 

 mannism, which embraces the opinions that acquired characters 

 cannot be transmitted, and that a portion of each organism is car- 

 ried unchanged from parent to offspring. He said, in his paper on 

 sex, " The hypothesis which assumes that the germ-plasma is pre- 

 cociously set aside in order to render it unmiscible with the somatic 

 plasma, and therefore immortal, is based upon a fundamental error 



