KOFOID: DEVELOPMENT OF LIMAX. 41 
a small protoplasmic mass budded off from a larger mass. This concep- 
tion of the cell division — tho derivation of a small part from a large 
part — dominated Blochmann’s nomenclature both of cells and of spirals, 
Accordingly, we find him designating a large mass of protoplasm, both 
before and after the small mass is budded off from it, by the same name, 
So also, when he comes to compare the spiral with the motion of the 
hands of a clock, he regards the small cell as moving away from the large 
cell, and designates the spiral accordingly. Other investigators of spiral 
cleavage — Lang (85), Conklin ('91 and ’92), Wilson (92), Heymons 
(93), Lillie (93) — have, like Blochmann, dealt with forms presenting a 
greater or a less inequality in cleavage, and have found it convenient to 
employ the system inaugurated by Blochmann for their nomenclature 
of cells and spirals, There has arisen in the usages of these various 
authors, however, considerable confusion in the detailed application of 
their nomenclatures to this basis of reference. Indeed, as I have pointed 
out in a previous paper (Kofoid, *94), an author is not always able to 
avoid inconsistencies, This state of affairs is confusing and extremely 
annoying to the student who wishes to make a comparative study of 
cell lineage. However much the introduction of a new system of nomen- 
clature is to be deplored, it seems to be justified for the following reasons. 
Cell lineage deals primarily with the descent and. Jate of cells, and is most 
conveniently traced by following the history of their nuclei; it is only 
secondarily concerned with the amount of yolk or protoplasm in the 
cells. The founding of a system of nomenclature, therefore, upon the 
relative sizes of cells, ignores wholly this fundamental proposition, and 
substitutes a basis of varying and uncertain nature, Furthermore, this 
system has caused the introduction, perhaps not necessarily, of the 
custom of designating cells of different generations by identical names ; 
thus 4 may be a cell of any one of a half-dozen different generations. 
In this, too, the principle of descent is ignored. 
Finally aud principally, tho basis hitherto employed affords mo solid 
ground whatever for comparisons, for it gives no logical method to be 
employed in cases of egual cleavage ; and its applieation must vary with 
the varying distribution of the large cells in different species of animals. 
Thus it comes about that * homologous” cells, i. e. those of identical 
descent, must according to this system be named differently in differ- 
ent animals. It may be that the system as applied by these authors 
does furnish a means, readily grasped by the eye and the mind, of fol- 
lowing the lineage in the particular form studied; but so long as it fails 
to form a basis for comparison, it is open to serious objection, It was 
