FERTILIZATION ON PARTHENOGENESIS. 169 



is very difficult to obtain a lot of eggs following fertilization or 

 membrane production that do not give a slight trace of fertilizin. 

 Seldom has the writer obtained as high as 100 per cent, of nor- 

 mally fertilized eggs or eggs possessing butyric acid membranes, 

 and unless this is realized there will still be eggs present con- 

 tinuously secreting this substance; and since a very few eggs 

 produce enough to be readily detected one may be led into an 

 erroneous interpretation of results. One must know the con- 

 dition of the eggs with which he is dealing. We may repeat 

 again the difficulty lies not in being able to obtain the reaction 

 but in producing a condition in mature eggs in which fertilizin is 

 entirely absent. 



2. Conditions Where Eggs May Be Partially Fertilized. 



The following experiment is very instructive and gives the 

 essential conditions of eggs at a few different points in the curve 

 of fertilization. Many such experiments have been performed, 

 each somewhat varied in the lengths of butyric acid exposures 

 yet the general results have always been the same. 

 July 22. Eggs collected and washed, and divided into seven lots. 



A. Control. 



B. Butyric acid exposure 3 seconds all jelly gone. 



C. Inseminated. 5 minutes later, short butyric acid exposure 



to dissolve jelly. 



D. Butyric acid exposure 20 seconds $5 per cent, membrane 



production. 



E. Butyric acid exposure i\ minutes, no membranes produced. 



F. Butyric acid exposure 3 minutes, no membranes produced. 



G. Butyric acid exposure 5 minutes, no membranes produced. 

 After butyric acid treatment all were poured into alkaline 



sea water to stop action of acid, and collected in graduated 

 cylinders. A. 0.5 c.c. eggs after treatment; B. 0.8 c.c. ; C. 0.9 

 c.c.; D. i.i c.c.; E. 0.7 c.c.; F. 0.5 c.c.; G. 0.4 c.c. 



10:30 A.M. began series of washings (Table IV). 



It will be noted in this series of eggs that in every case with 

 the exception of lot C, fertilization is possible at least to a limited 

 extent, and that in all, fertilizin was still being produced after 

 eight washings, yet none of these eggs possessed a trace of the 



