48 THE VICTORIAN NATURALIST. 



SOME ANIMALS REARED FROM DRIED MUD. 



By J. Shephard. 



(Read before the Field Naturalists' Club of Victoria, Wth July, 1898. J 



About March last I visited a locality at Brighton where, in the 

 past, plenty of " pond life " was to be had. Owing to the dry 

 season the pool had completely disappeared, and even the fairly 

 copious rain of a few days before hid only damped the ground 

 slightly ; however, I took away a 2-oz. bottle filled with the dried 

 mud from the deepest part of the excavation. Having ]ireviously 

 tried to rear animals from similar material (but without success) 

 by placing it in surface water collected for the purpose, I decided 

 to wait for the rainy season, and then let the rain fall on the dry 

 earth and so simulate natural conditions. About the 20th of 

 May the rain came, and was added to a bottle holding the dried 

 mud. Examined from time to time, only minute Protozoa were 

 found until ten days had elapsed, when both Entomostraca and 

 Rotifera were present in numbers. The first rotifer to appear 

 was Brachionus pnla, a not uncommon species. In connection 

 with this form I would call attention to some features noted. 

 Mr. Rousselet read a paper in January, 1897, on ^^ Brachionus 

 Bakeri and its Varieties," before the Queckett Microscopical Club, 

 in which he showed how no less than 13 named species might 

 be regarded as varieties of B. Bakeri, the chief point relied 

 upon for the specific distinctions in these so-called species being 

 the form of the spines, more particularly the posterior ones. 

 Having B. pala under observation for some time, and examining 

 a considerable number, I found that the earliest to appear 

 possessed very short posterior spines and a soft and flexible lorica. 

 Later on specimens with longer posterior spines and less trans- 

 parent loricffi appeared, though a number with short spines were 

 mingled with them. A gathering from the pool when rain had 

 fallen, at a later date, showed B. jmla with spines at least four 

 times as long as in the forms from the cultivation. 



Mr. Rousselet says that all the varieties of B. Bakeri are never 

 found together, but one or two affect each locality, and apparently 

 he regards them as products of certain sijecial conditiois prevail- 

 ing in dift"erent localities. In view of the observations now men- 

 tioned, where the animals developed for a number of generations 

 under the same conditions, I would suggest that these varieties 

 are possibly stages in the growth of the individual, or that the 

 descendants of those first produced from the resting eggs vary as 

 successive generations are born. I had a B. pala under obser- 

 vation at the moment of hatching, and saw there was only one 

 posterior spine. This would lend to indicate that the spines 

 develop with age. Another rotifer, appearing a little later than 

 B. pala, also exhibits similar va rialion of form — namely, a species 



