386 Prof. H.C. Bastian. On the Occurrence of certain [Feb. 14, 
with the forms assumed by the Ciliates taking origin from such a source. 
Thus, if I can prove that two or more wholly different forms of Ciliated 
Infusoria can be produced from transformations of the substance of the eggs 
of a particular Rotifer, I shall not only establish the reality of heterogenesis 
in one of its most striking phases, but shall go far to show that the varied 
forms even of such organisms as the Ciliata are as much the outcome of their 
molecular composition and of the laws of “polarity ” as are the various forms 
assumed by crystalline matter. 
(1) The transformation of the entire contents of a Hydatina egg into a great 
Otostoma.—Having witnessed on very many occasions the stages of this 
remarkable transformation of the contents of a Rotifer’s egg into a Ciliated 
Infusorium, I am desirous of acquainting the Royal Society with the simple 
procedure needful to enable zoologists to study for themselves the series of 
changes leading to a result which many of them may be disposed to deem 
incredible. 
All that is necessary is to procure a good stock of these large Rotifers 
by placing some surface mud, having a coating of Euglene, from a 
ditch in which Hydatine are known to exist, into a glass bowl, and to pour 
thereon water to a depth of about 4 inches. In the course of two or three 
days (with a temperature of 16° or 17° C.), if the Hydatine are abundant, a 
good crop of their large eggs will be seen at the surface of the fluid, where it 
is in contact with the glass. The difficulty is to find suitable sites in which 
the Hydatinz are really abundant. An excellent source from which I 
formerly obtained supplies has since been destroyed. 
By the aid of a scalpel passed along their track for a short distance, 
groups of 20 to 30 eggs may be taken up at one time, and gently pressed 
off the edge of the blade into a small, white stone pot full of water. Some 
of such small masses of eggs (mixed, perhaps, with a few Euglenz) will 
float, and others will sink. After seven or eight of these masses have been 
gathered and deposited, the cover should be placed upon the pot so as to cut 
off from the eggs all light rays, beth visible and invisible.* 
If the supply of eggs will admit of it, two other pots should be similarly 
charged; but if there are not enough eggs for this purpose, the two other 
pots should be charged on successive days with fresh batches of eggs. The 
larger the supplies of new-laid Hydatina eggs the more convincing will be 
the result. Thus on one occasion when my supply was very abundant, 
* Full details as to the best means of obtaining supplies of Hydatine, dealing with 
them, and subsequently obtaining the largest proportion of freshly laid eggs, will be found 
in my “Studies in Heterogenesis,” pp. 125 and 286. 
