392 Cilated Infusoria within the Eggs of a Rotifer. 
in finding plenty of material with which to work, and who may be skilled, as 
I am not, in modern methods of making sections of such minute objects as 
Hydatina eggs, doubtless much highly interesting information will be forth- 
coming of a nature to satisfy cytologists as to the histological details of the 
transformation in question. These minute details, however, I must leave to 
others; all I claim is to have established the fact itself of the heterogenetic 
origin of different kinds of Ciliated Infusoria from the eggs of one and the 
same Rotifer. The seeming utter improbability of such a fact may be taken 
as some measure of its enormous importance for biological science, when we 
consider the far from simple structure of these unicellular Ciliates, that no 
kinship of any sort, in the ordinary sense of the word, exists between them 
and Rotifers, and, further, that even totally different forms of Ciliated 
Infusoria are capable of being produced from the egg-substance of a 
Hydatina according as it becomes transformed as a whole, or only after 
having undergone segmentation into a varying number of small spherical 
masses. 
DESCRIPTION OF PLATE. 
(PLATE 7.) 
Figs. 5 and 14 are magnified 125 diameters, while all the others are magnified 
250 diameters. 
Fie. 1.—A newly-laid egg, or “ gemma,” of Hydatina. 
Fias. 2, 3, 4.—Different stages in the transformation of the egg-substance into a motzonless 
ageregate of vesicles and granules, different from anything which is ever to be 
seen during the normal development of the Hydatina egg. . 
Fig. 5.—Six Hydatina eggs and an empty egg-case, taken from one of the pots after 
36 hours. The three central eggs are in the vesicular stage of transformation 
into Ciliates, while the three others show different stages in the development of 
Hydatine. 
Fic. 6.—An embryo Otostoma which was seen slowly revolving within a Hydatina egg- 
| case, taken from a pot after the expiration of three days. 
Fic. 7.—An Otostoma escaping from the egg-case after the application of a weak iodine 
solution. 
Fie. 8.—An Otostoma which was seen to rupture, and emerge from, an egg-case. Killed 
after about half an hour. Cilia now numerous, and well-developed. 
Fie. 9.—A starved Otostoma, showing the small ear-like mouth, a very large elongated 
nucleus dimly indicated above and to the left, and fine longitudinal surface 
markings caused by rows of cilia. 
Fig. 10—A small fully-developed Otostoma in a starved condition, showing small ear-like 
mouth and large nucleus. 
Fie. 11.—A rather small Otostoma encysted. 
Fig. 12.—Segmentation of a Hydatina egg into a number of large vesicular bodies. 
Fic. 13.—Presumed later stage of such an egg as is shown in the last figure, now 
divided into about 20 unequal, evenly granular, spherical masses, such as were 
seen in contiguous eggs to give rise to minute embryo Vorticellze. 
Fic. 14.—Three empty egg-cases (save for one remaining sphere), with a number of the 
young Vorticellz in different stages of development. 

