158 CARL RICHARD MOORE. 



result in the production of membranes; we have also noted that 

 insemination is followed by a certain amount of abnormal cleav- 

 age and a corresponding percentage of aberrant larvae. Such 

 conditions were spoken of as partial fertilization. We see many 

 evidences in the literature of such quantitative aspects of both 

 artificial parthenogenesis and fertilization. These conditions 

 may be brought about either by treatment essentially effecting 

 the normal condition of either parent cell before union an 

 internal modification or by allowing union of the two elements 

 in an environment in which the normal processes involved in 

 union are modified an external modification. No attempt to 

 review the very many conditions and instances of the production 

 of such abnormal conditions will be made. It is sufficient to 

 point out the fact that very gross abnormalities have been 

 produced by modifying the processes of fertilization. One of 

 the best demonstrations of the quantitative effect of artificial 

 agents in starting off the dormant mechanism of the egg is that 

 given by R. S. Lillie ('15). 



Lillie found that a brief exposure of unfertilized eggs of Asterias 

 forbesii to temperatures ranging from 32 C. to 38 C. caused 

 membranes to be produced. If these eggs were then treated 

 with hypertonic sea water development ensued and larvae were 

 produced in large numbers. Further than this the effect of the 

 hypertonic solution could be replaced by a second exposure to 

 high temperatuies or by butyric acid. Either was capable of 

 partial imitation that could be completed by a further treatment 

 of the same or other agent. In the sea urchin however the 

 conditions seem to be more specialized. Optimum conditions 

 for exposure to butyric acid results in the production of mem- 

 branes and at this time fertilization is impossible. But a longer 

 exposure does not result in membrane production and in this 

 condition a certain amount of reaction between egg and sperm 

 is evident from the fact that cleavage and larvae are produced. 



The physiological differences in the two cases will be partially 

 dealt with in Sec. V. 



(a) Cytological Observations. Cytological preparation of these 

 instances of partial fertilization are extremely interesting, and 

 vary in essentials but little from those previously described by 



