No. I.] THE EGG OF UMAX AGRESTIS. 229 



During the early fall months I collected large numbers of 

 Limax in old vegetable gardens in Bryn Mawr and under stones 

 that lay along the banks of an open drain. These slugs can be 

 collected out of doors as late as the middle of December. Much 

 of my material was collected late in the evening, with the aid 

 of a lantern, and in the early morning hours when the slugs 

 were on their way to their hiding places. During the winter I 

 was able to collect Limax in small numbers in the carnation 

 beds of a neighboring hothouse. 



The slugs were kept in the laboratory in a large Wardian 

 case filled with living plants, and were fed on cabbage leaves, 

 plantain, dock, and various vegetable roots. Under these con- 

 ditions the slugs lived for some time in an apparently healthy 

 condition and yielded eggs in abundance. Sooner or later, 

 however, slugs that are kept in confinement become infested 

 with parasites, even when the greatest precautions are taken as 

 to cleanliness and an abundant food supply. The ovo-testis 

 becomes infested with parasitic protozoa, which are sometimes 

 found in swarms in the capsules after the eggs have been laid. 

 A parasitic thread worm is also found in the reproductive 

 organs of Limax. 



Eggs enclosed in capsules that contain even a great many 

 parasites are by no means necessarily abnormal in their devel- 

 opment ; indeed, they often give rise to normal embryos. In 

 order to avoid any complication that might result from the 

 study of abnormal eggs, however, fresh relays of slugs were 

 constantly supplied from time to time in place of the old ones. 



Preparation of Material. 



The Q.gg of Limax is imbedded in an almost liquid jelly 

 contained in a large, tough capsule. The Qg% is immediately 

 surrounded by a somewhat denser layer of jelly, which adheres 

 very closely to its surface. 



At first I attempted to preserve eggs in the capsules, and for 

 this purpose Flemming's solution and chromic acid (i per cent) 

 were chiefly used. The killing fluids quickly penetrated the 

 capsules so that the eggs were perfectly preserved. The cap- 



