PROCEEDINGS OF THE SOCIETY. 
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the necessary material in London rendered such exhibitions impractic- 
able. That evening he proposed to refer to the question of the 
adhesion and attachment of many fresh-water organisms to various 
animate and inanimate objects in the water. At first sight it might 
appear a very simple matter that a minute plant or animal should 
attach itself to' some other body, but when it was remembered that 
nearly all groups of aquatic organisms were originally almost certainly 
either free-floating or free-swimming, it was evident that many special 
modifications had been required corresponding with the very varied 
modes of attachment which were represented. Considering the subject 
from the point of view of the degree of adhesion or attachment it could 
be stated generally that the numerous cases of permanent attachment 
were due to some exuded material which had the property of hardening 
under water. There were probably many different kinds of such 
substances produced, and if their exact nature could be determined by 
some application of micro-chemical analysis, the results might be of 
far-reaching importance. The cases of semi-permanent attachment, 
such as Hijdra for example, were due usually to the production of 
glutinous secretions which did not harden under water, but remained in 
a “ tacky ” condition. The most varied and interesting kinds of attach- 
ment were, however, those of a temporary nature. The simplest types 
were probably those due to the slightly sticky nature of protoplasm 
itself, and many examples of this could be given among the Rhizopoda, 
Flagellata, &c. A striking illustration was the use of a flagellum, as in 
Boclo, for adhering to and gliding upon the glass slide or cover-slip, 
and no doubt also upon water plants, &c. Another type of temporary 
attachment was brought about by a secretion from special glands, such 
as occurred in the toes of Rotifers and on the back of the head in Sida 
crystallina. True suckers were used for attachment in some cases, e.g. 
Argidus , and many leeches, while hook-shaped hairs and setae were 
naturally the means employed in numerous other cases, especially among 
the Entomostraca, e.g. Simocephalus , Cyclops , &c. But perhaps the 
most peculiar of all methods of temporary attachment was that in 
which the organisms, although heavier than water, made use of the 
surface-film of water for support. This was rendered possible by the 
water-repellent nature of various specialized portions of the body, setse, 
scales, &c., which produced capillary depressions when brought into 
contact with the surface-film, and thus enabled the organisms to take 
advantage of the upward pull due to surface tension. Examples of this 
method of attachment were Hydra , Scaphoid er is , Notodromas , &c. 
Mr. Scourfield then referred in detail to the various objects ex- 
hibited. He commented on the fact that, unlike any previous Pond- 
Life Exhibition he could remember, not a single example of the 
Polyzoa was being shown. On the other hand, two of the worm types — 
Chsetogaster and Mesostomum were being exhibited which had not been 
the case for at least some years past. 
On the motion of the President, a hearty vote of thanks was 
accorded to the Members of the Quekett Microscopical Club, and to the 
Fellows of the Royal Microscopical Society who had kindly exhibited 
specimens, and to Mr. Scourfield for his remarks. 
