FORMATION OF NEW COLONIES OF MEGALOTROCHA. 183 



The animals are however attached to the stem by a kind of mu- 

 cilaginous substance secreted by a gland in the foot. This sub- 

 stance forms a thin layer on the stem over the area of attach- 

 ment of the colony. The adult colonies usually contained eggs 

 or at least soon produced them after being brought into the 

 laboratory. The eggs are attached to the mother by means of 

 an adhesive gland situated a short distance posterior to the open- 

 ing of the cloaca. Usually only one or two eggs are found 

 attached to a single individual, but sometimes as many as four 

 were observed. 



The method of egg deposition is interesting. The egg rapidly 

 increases in size in the region of the vitellarium, and then passes 

 slowly down the oviduct to the cloaca. When the egg with its 

 large germinal vesicle has reached this region the animal bends 

 towards the dorsal side in such a manner that the adhesive gland 

 touches the protruding egg. The animal frequently remains in 

 this position for some time, often bending still farther so that the 

 corona points towards the foot. In this way the end of the egg 

 is firmly pressed against the adhesive surface of the gland. The 

 animal now slowly and by repeated attempts straightens itself and 

 at the same time the egg is pulled from the cloaca and remains 

 attached to the mother, where it undergoes development. One 

 egg has scarcely been deposited before another can be seen en- 

 larging in the region of the vitellarium. Eggs begin to form in 

 all the individuals of a colony at approximately the same time. 

 But an interval of three or four hours may elapse from the time 

 the first egg is laid until all the animals have deposited eggs. 

 During this time the individuals which deposited the first eggs 

 have often deposited a second. This overlapping of broods is 

 important, as will be pointed out later, in keeping the size of the 

 colonies more nearly constant. 



The length of time required for the young rotifers to hatch 

 varies somewhat, depending on the temperature and other condi- 

 tions. Usually they hatch in three or four days after deposition. 

 The young rotifer when fully formed can be readily seen through 

 the transparent egg membranes. For some hours before hatch- 

 ing frequent contractions of the body and movements of the cilia 

 and mastax may be seen. By means of these contractions the 



