262 
TRE STUDY OF DIATOMS. 
An prise | tothe Study of the | Diat ez, | By | FREDERICK WM. 
LLS, . RONLS | 2s | S| with at Bibliography, | rif rae ests, 
ERM gra | London : | Tliffe & Son Ors Pa B 8vo. 
xii +243 pag 
This little a is modestly styled an ‘ Introduction’ by its author, 
and it is truly such, being very elementary in nature. Of the 240 pp- 
comprising the text, the work proper only occupies 77 pp., the 
remainder, pp. 78-240, being the Bibliography of Mr. Julien Deby. 
With limited space at our disposal, we can but glance at the salient 
points of the work. On p. 3 we are informed that Diatoms ‘have 
been known to survive nearly a quarter of a century in their natural 
element,’ etc.; this quoted instance of ‘longevity’ omits the 
important fact that in that long period there must have been many 
cycles of generations—each of comparatively brief existence. In 
chapter ii. the structure, internal and external, of these lovely little 
organisms is but cursorily treated; and, in lieu of information on 
the chemistry of the endochrome, references only are given, and 
those to authors inaccessible to ordinary British readers. The third 
chapter, on the movements of Diatoms, i " spe fairly rendered; bear 
the quotations well chosen. he fourth 
based upon that of Prof. H. L. Smith lone: “of: the few American 
authors whom it is safe to follow !), which will be found very useful 
for reference by any student. With respect to the modes of repro- — : 
duction, it ‘goes without saying’ that the dicta of the illustrious _ 
DeBary represent practically all that is known. Many diatomists 
will, however, not accept the new-fangled term Zygosperm as a sub-— 
stitute for the older word Zygospore—and the mass of practical 
workers will object to the conclusions quoted from Dr. Dallinger. 
are sO important that we cite them. He says, pp. 39-4% 
binary sub-division cannot take place in genera with unequal valves, 
as it is universally acknowledged that the two new valves which are 
formed in the process of binary sub-division must stereotype them- 
_ selves on the old valves ’—this is exactly what does zof take place! 
A very distinguished observer writes to us, ‘ the young valves never 
stereotype themselves om the parent valves . . . they are 
unquestionably developed within the parent valves.’ The use of the 
word ‘stereotype’ by Dr. Dallinger appears to be a lapsus calami, — 
as, if anything approaching a stereotyping occurred in vegetative 
_ self-division, the markings would also ‘stereotype’ fescapbion’ ys : 
forms d 
this our friend writes, ‘both th 7 : 
not acquire their perfect streistisiy until each has emerged from its 
parent Wave, «6 = and why each y young valve and not 
_ before, _ completes its structural ad n more than 
