1224 General Notes. [ December, 
The general law of fertilization, stated by Strasburger for plants, 
and which we see from the above holds also for animals, is: 
Fertilization consists essentially in the conjugation of male with 
female nuclei ; these are ordinary cell nuclei; and the cytoplasm 
takes no part in the process. 
It is therefore erroneous to speak in a general way of the cell 
protoplasm as carrying the hereditary powers. Of the many 
writers who have treated this subject, only three or four have 
given more definite statements. Nageli calls that substance zdo- 
plasm, which controls or determines the specific characters of the 
cell, but does not limit it to the nucleus as does Kolliker and 
Born. Strasburger distinguishes between two sorts of idioplasm, 
that of the cell (cyto-idioplasm), and that of the nucleus (karyo- 
idioplasm). 
In the nucleus exists a substance of definite morphological and 
chemical character, known as nuclein or chromatin. With this sub- 
stance the idioplasm must be conceived as connected. (1) The chro- 
matin of the male pronucleus unites with that of the female pro- 
nucleus to form the chromatic figure’ of the segmentation nucleus. 
According to Van Beneden there is no union, but the chromatin 
loops of the pronuclei remain separate so as to give the segmen- 
tation nucleus a double character, morphologically, one-half being 
distinctly male and the opposite, female ; and this holds true of all 
its offspring. But Nussbaum found that before segmenting, the 
nucleus has a stage in which the chromatin forms a single fila- 
ment. Furthermore Van Beneden’s own figures do not seem to 
Kolliker, to support his view. (2) The processes of karyokinesis 
show how important it is that the chromatin should be divided 
between the daughter nuclei in a definite way. It is natural to 
suppose that to distribute the hermaphrodite idioplasm to the 
daughter cells, so that each shall get its proper amount, must be a 
delicate process. 
We have now to inquire how the idioplasm effects the work of 
heredi 
In the development of an egg into an adult there are two mo- 
ments at work, First, the cells multiply until a Saran pres number 
of cells needed by the organ is produced; second, these cells 
are separated into groups and are differentiated into the various 
| tissues. We may refer to the cambium zone of plants for a 
' familiar illustration. 
2 The structural characters of any organism depend o 
_ factors: (1) cell division, and (2) cell growth; both as a a 
quantity, a lity. 
Cell: multiplication, if great, will produce a large organ; if less, 
Tas The multiplication may be uniform or may be more 
certain | 
A ts. Thus in the arm rudiment, five points of 
id cel Cater opr with points of rest, and the five fingers 
cell division ~~, take place in one, 
