36 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
immersion in water. Finally, the author discusses the numerous 
colour-variations, and finds that they are protective adaptations to the 
colour of the environment, and established, he believes, by natural 
selection. 
New Mode of Respiration in Myriopoda.* — Mr. F. G. Sinclair 
(formerly F. G. Heathcote) describes a special organ in the Scutigeridae. 
Each consists of a slit bounded by four curved ridges and leading into 
an air-sac. From this sac a number of tubes are given off, which are 
arranged in two semicircular masses. The ends of the tubes project 
into the pericardium in such a manner that the ends are bathed in blood 
and aerate it, just before it is returned into the heart by means of the 
ostia. In the living animal the blood can be seen through the trans- 
parent chitin of the dorsal surface surrounding the ends of the tubes. 
The tubes each branch several times, and each tube is lined with chitin, 
which is a continuation of the chitin of the exo-skeleton. Each tube 
is also clothed with cells which are a continuation of the hypodermis. 
The tubes end in a blunt point of very delicate chitin. These organs 
are supposed to be respiratory since there are no other organs that 
can be supposed to have that function ; the chitinous lining grows thin 
and membranous towards the end, and so affords a good opportunity 
for interchange of gases ; the ends are bathed with blood ; the tubes 
are filled with air, and the organ is so placed as to aerate the blood 
just before it returns to the heart. It is probable that these organs 
are a recent modification, for they are arranged on the dorsal scales, 
or, in other words, are not arranged in correspondence with the 
mesoblastic or primitive segmentation. 
This mode of respiration differs from that of other Myriopods in 
the following points — the tubes are collected into one definite organ, 
instead of being distributed about the body ; they have no spiral 
thread ; in acting on the blood just before it returns to the heart. 
After pointing out the resemblances to the tracheae of other Myrio- 
pods and the resemblances to and differences from the tracheal lungs of 
Spiders, the author suggests that the respiratory organ in Scutigera 
holds a position intermediate between the tracheae of Myriopods and 
the lungs of Spiders. He agrees with Leuckart in thinking that the 
tracheae have developed into the lungs of Spiders and Scorpions ; the 
respiratory organs of these forms make a series, the low est term in which 
are the tracheae, then the organ of Scutigera, then the lungs of Spiders, 
and lastly those of Scorpions. 
Anatomy of Ghilopoda.f— Dr. C. Herbst first describes the various 
glands — the head-glands of Scutigera, Lithobius, Henicops, and Scolo- 
pendra, the poison-glands, tbe glands of the terminal segment, the coxal, 
anal, and pleural glands. On the head two different types occur. In 
some the sacs or tubules empty their secretion directly to the exterior, 
as in Scutigera, and in two sets found on Litliobiidae. In others there 
are long efferent ducts, which are either terminally expanded in a complex 
lobed mass, as in one of the sets occurring on Lithobius and Henicops, and 
four of the sets on Scolopendra, or end simply in little glandular sacs, as 
* Prop. Roy. Soe. Lond., 1. (1891) pp. 200-1. 
t Bibliotheca Zool. (Leuckart and Chun), is. (1891) 42 pp. (5 pla.). 
