612 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
predicate tlie precise attributes of whole classes of phenomena, is to run 
counter to the very genius of the subject. For what do we mean by- 
evolution if not that life is labile, never-resting, protean in its variety ? 
If we are to have a definition at all, Mr. Bourne would suggest that a 
cell be defined as a corpuscle of protoplasm which contains a specialised 
element, nuclein. Cells, as thus defined, are not only of various kinds,, 
but are variously compounded together. (1) There are those which are 
discrete, or corpuscles whose protoplasm is not in union with that of 
any other corpuscle. (2) Others are concrescent, or are corpuscles 
whose protoplasm is in union with that of other corpuscles. Discrete 
cells may be divided into those that are independent, like the uni-nuclear 
Protozoa, the mature ovum, or leucocytes. Coherent cells, on the other 
hand, are those which are in close apposition to others, but not organi- 
cally in union with them, as for example, the blastomeres of many 
developing embryos. Concrescent cells are either continuous or conjunct. 
The former have the protoplasm fused but the nuclei separate, as in 
Myxomycetes , or Opalina , while conjunct cells are those which have a 
protoplasmic body of definite outline and are united among themselves 
by fine bonds of protoplasm. In concluding an article of great interest 
Mr. Bourne points out that even if the case which is based largely on 
the history of the development of Peripatus be proved to the hilt, it will 
after all be an isolated case of secondary significance ; merely another 
addition to our experience of the very various phenomena displayed in 
organic growth. For thousands of instances point to the fact that normal 
growth is effected in a very different way, by mitotic division of the 
nucleus preceding and directing the formation of a discrete or concrescent 
cell-corpuscle. The recent researches of cytologists are too many, too 
good of their kind, and too consistent to admit of any other conclusion. 
Heterotype Nuclear Divisions in Animals and Plants.* — Prof. J. 
B. Farmer and Mr. J. E. S. Moore have an essay on the essential 
similarities existing between the heterotype nuclear divisions in animals 
and plants. They point out that there has been little or no recognition 
of the fact that in one and the same species there may exist considerable 
range of variation, both in the actual form and in the mode of develop- 
ment of the individual chromosomes. They point out that this is a 
matter of interest, since it affords evidence of variations occurring at an 
especially important period in the life-history of the organism, and they 
suggest that it may serve to throw some further light on the essential 
stages in the metamorphoses through which the chromosomes indi- 
vidually pass. The observations here detailed have been chiefly based 
on a study of the spermatogenesis in Triton and the pollen-mother-cells 
of Lilies. Those who have read the recent contributions to our Trans- 
actions by Miss Sargant and Prof. Farmer will readily understand that 
the details given by the present authors are not amenable to condensa- 
tion. The results which they have obtained from animal and plant- 
cells respectively agree so closely, even in the most minute details, that 
it seems impossible to doubt that the entire process of heterotype mitosis 
is essentially the same in both kingdoms. The authors, however, leave 
it an open question whether this identity is due to phylogenetic causes* 
* Anat. Anzeig., xi. (1895) pp. 71-80 (29 figs.). 
