ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
47 
The great gap in Darwinism appears to Mr. Thomson to be the absence 
of a theory of variation. 
Taking, perhaps, a somewhat more charitable view than some take, 
he says of Prof. Weismann that he has repeatedly changed his position 
because he is progressive, but he assigns to him the credit of having 
taken several bold steps into the darkness. With regard to the criti- 
cisms on the German naturalist, he says that one has simply to tie them 
into bundles, label them misunderstandings, see page so-and-so of the 
‘ Germ-plasm,’ and burn them. At the same time he allows that he 
feels that some difficulties — for example those concerning syphilis — if 
properly stated and marshalled, may lead to yet farther concessions 
from the Professor of Freiburg. He says in conclusion, very wisely, 
that, while the general conception of evolution stands more firmly 
than ever as a reasonable modal interpretation of nature, there is great 
uncertainty in regard to almost every question concerning the factors 
in the evolution process. We are not where we were forty years ago, 
we have become more aware of our ignorance and of the complexity of 
the problem. 
Marine Fauna of Houtman’s Abrolhos Islands.* — Mr. W. Saville- 
Kent describes this group of islands as a small archipelago chiefly of coral 
origin. The ordinary Australian rock oyster, Ostrea glomerata, occurred 
there in tolerable abundance and under conditions that would justify its 
being made the subject of systematic cultivation. The site selected for 
experiments in acclimatisation was in Shark’s Bay, in the neighbourhood of 
extensive banks of Turbinciria. With regard to this genus of Madrepores, 
Mr. Saville-Kent finds that it is the one which, in Australian waters, 
enters most extensively into the composition of coral reefs in the colder 
or extra-tropical limit of their distribution. Although the group called 
Houtman’s Abrolhos lies some 2° south of Shark’s Bay, the character 
and composition of the coral reefs prove to be entirely distinct. In 
place of the extra-tropical Turbinarise the corals of the Abrolhos reef 
comprise, as in the essentially tropical districts, numerous varieties of 
branching Madreporse mingled with many species of intra-tropical reef- 
building species. A still more remarkable phenomenon is the presence 
on this reef of three of the most valuable economic species of Holo- 
thurians, identical with types that are systematically collected in Torres 
Straits and throughout the northern half of the Queensland Great Barrier 
Reef. The anomalous character of the marine fauna of Houtman’s 
Abrolhos can only be accounted for by the assumption that an ocean 
current setting in from the equatorial area of the Indian Ocean penetrates 
as far south as this island group. 
Dispersal of Marine Animals by means of Seaweeds. f — Mr. R. 
Yallentin was led, whilst surface-netting, to examine a large mass of 
Fucus serratus , which was being swept away to sea by an ebbing tide. 
On securing it he discovered a large stone attached to the base ; numerous 
specimens of Hydroids and Polyzoa were also noticed attached to the 
fronds of this seaweed. Since then he has paid attention to floating 
seaweed when out in his boat, and has recorded his observations in a. 
* Rep. Brit. Ass., 1895, pp. 732-3. 
t Ann. and Mag. Nat. Hist., xvi. (1895) pp. 418-23. 
