ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
327 
and on the relation of the spontaneous generation theory to the general 
theory of evolution. We have not noted any new facts in it. 
B. INVERTEBRATA 
Action of Nicotin on Invertebrates.*— Miss M. Greenwood has 
made a study of the effects ot nicotin on certain Invertebrates. The 
toxic effect on any organism is mainly determined by the degree of 
development of the nervous system. For Amoeba or ActinospJiserium it 
cannot be regarded as paralysing ; it is rather inimical to continued 
healthy life. The higher forms show that the nervous actions which 
imply co-ordination of impulse are the first to be stopped- In the 
Medusae spontaneity, irradiation of impulse, and direct motor activity 
are affected successively. In still higher forms the paralysing action of 
nicotin is preceded by a phase of stimulation ; this becomes marked in 
Ophiurids and Crinoids, and is very characteristic of the poisoning of 
Palsemon and Sepiola. t 
As this positively exciting action becomes noticeable, nicotin becomes 
more and more a medium in which life is impossible. For example, 
Amoeba is not killed at once by a 1 per cent, solution of nicotin tartrate. 
Hydra dies rapidly in such concentration, but will live overnight in 
•05 per cent. ; such a solution kills Lumbricus , which tolerates *01 per 
cent, for only a few hours. * 05 per cent, solution paralyses Asterias 
and Antedon in half an hour ; * 005 per cent, in less than a minute so 
injures Sepiola that there is no subsequent recovery. 
When very simple animals die under the action of nicotin death is 
often associated with injury of their substance so that it tends to dis- 
integrate. The definite poisoning that occurs in higher types has some- 
times, as one of its after-effects, a lingering trophic disturbance. An 
extreme case is presented by Palsemon, where there may be a progressive 
death of tissues from behind forwards. 
Notwithstanding the general relation of the action of nicotin to the 
stage of development of the nervous system, there is an appreciable 
amount of difference in animals placed near one another in systematic 
classifications. 
The Trochozoa.f — M. L. Roule proposes a new phylum of the 
Coelomata to include some worms, the Mollusca, Bryozoa, and Brachio- 
poda. Its systematic position may be seen from the following table : — 
{ Platyhelminthes 
N emathelminthes 
Trochozoa 
Arthropoda .. .. Arthropoda 
I Chaetognatha 
Echinodermata 
Hemichordata 
Urochordata 
Vertebrata 
The Trochozoa are characterized by the constant appearance (except 
in cases of abbreviated development) of a larva which belongs to the 
Coelomata . . 
* Journal of Physiology, xi. (1890) pp. 573 -605. 
t Ann. Sci. Nat., xi. (1891) pp. 121-78. 
