198 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
tissues may have a definite relation to the normal pigmentation of 
those tissues. These facts tend to confirm the conclusion to which 
Dr. Eisig has been led, that the normal pigments are to he inter- 
preted as, to a considerable extent, excretory in nature. 
The author commences his descriptive portion with an account of 
the normal characters of the living zooecium in the species investigated, 
and then describes the process of absorption of various pigments. In 
his third section he deals with the formation of the “ brown body,” and 
the further history of the absorbed pigments. 
Leucocytes readily absorb indigo-carmine ; they do not take up 
Bismarck-brown directly, but abstract it at a later period from other 
tissues ; they are not in the least affected by carmine in suspension, or 
by carminate of ammonia. The pigmented granules of the stomach and 
caecum of Bugula avicularia readily take up indigo-carmine, carminate of 
ammonia, or Bismarck-brown, while the same jiarts of B. neritina are 
quite unaffected by the first and last of these pigments. The funicular 
tissue of B. neritina is deeply pigmented and readily takes up Bismarck- 
brown ; in the other form investigated this tissue was generally colour- 
less, and did not take up Bismarck-brown in the manner characteristic of 
B. neritina. Young, slightly differentiated tissues of growing points 
readily take up considerable quantities of carminate of ammonia and of 
Bismarck-brown. 
The author, before proceeding to consider the corroborative work of 
other observers, points out that it can hardly be doubted that the 
pigments experimented with were actually excreted. In B. neritina 
Bismarck-brown was taken up so freely by the funicular tissue that it at 
first appeared extremely improbable that the animals could recover, but 
at a later period the pigment was deposited in an ajjparently insoluble 
form in various parts of the funicular tissue, the remainder of which was 
quite free from it. Similarly the alimentary canal of B. avicularia was 
able to rid itself of Bismarck-brown by a process which involved the loss 
of its normal granules, inclosed in spherules. Such spherules are of 
normal occurrence in this species, and are probably concerned in the 
excretion of some of the normal pigments of the canal, though their 
function may be in part digestive. 
Polyzoa of the St. Lawrence.* — After an interval of three years the 
Bev. T. Hincks continues his study of Arctic forms. Flustra solida 
Stimpson is discussed at some length. Menibranipora annifera Hincks 
was, it now appears, first described from immature specimens ; the author 
now revises and completes the diagnosis from perfect forms. Nine other 
forms are more or less briefly discussed. 
Arthropoda. 
a. Insecta. 
Swimming Butterflies-t — Prof. S. Klemensiewicz tells, under this 
more sensational than accurate title, how he watched white butterflies 
( Pieris rapse) fluttering in hundreds over the great lake of Czarny Staw, 
Many sank on the still surface of the water, rested for half a minute, 
* Ann. and Mag. Nat. Hist., ix. (1892) pp. 1 49—57 (1 pi.), 
t Verb. Zool.-B.it. Gesell. Wien, xli. (1891) p. 87. 
