539 
proximately equal quantities of massive chromatin in the two daughter 
nuclei. 
The phenomena observed in Opalina intestinalis and O. caudata 
suggest that Hertwig’s distinction between trophochromatin and idio- 
chromatin may here apply. The massive chromatin, which is thrown 
away bodily before the sexual phenomena are completed, seems plainly to 
be not reproductive. Accepting Hertwig’s term we will call it trophic. 
In the binucleate Opalinas, from time to time thruout the year 
division of the body follows division of the nucleus, tho only after con- 
siderable delay, and temporarily uninucleate daughter individuals are 
formed. If, as their appearance suggests, the several massive chromo- 
somes have constant and persistent differences in functional value, then 
it is necessary to guard carefully their division; otherwise the massive 
chromatin in one uninucleate daughter cell would differ essentially from 
that of its sister cell, and disaster would follow. 
In the multinucleate Opalinas it is less important to have the nuclei 
all exactly equivalent, for among the many nuclei, in spite of occasional 
division of the body, there will doubtless be represented in sufficient 
quantity each sort of massive chromatin, if indeed in these multinucleate 
Opalinas there be differences in functional value between different por- 
tions of the massive chromatin. In the spring, when the period of se- 
xual reproduction approaches, uninucleate individuals are formed but 
they persist for only a short time. In both the multinucleate and binu- 
cleate species, all the massive chromatin is thrown away at this time, 
the granular chromosomes become more compact, and growth processes 
are at a low ebb, until the readjustments resulting from the sexual pro- 
cess are accomplished. Then new massive chromatin is formed from the 
granular chromatin, much as in Paramecium the trophic macronucleus 
arises from an originally idiochromatic micronucleus. The difference in 
the care exercised by binucleate and multinucleate species in dividing 
the trophic massive chromatin is probably due to the less need of exact 
equivalence of trophic qualities between the nuclei of forms which for 
all but a week or so in the year live in a multinucleate condition. 
Further discussion of these conditions and relations I prefer to post- 
pone until I shall have followed both sets of chromosomes in O. antillien- 
sis thru the sexual reproductive phases of the life cycle. 
II. Opalina antilliensis, new species. 
In the rectum of the large toad, Bufo aguat, of Jamaica, West 
Indies, are generally many individuals of an unusually interesting Opa- 
1 I am greatly indebted to Professor E. A. Andrews of Johns Hopkins Uni- 
versity for half a dozen living specimes of this toad, as will as for other Amphibian 
material from Jamaica, containing Opalinas of much interest. 
