ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
413 
the infracarcliac lobe. Thus the associated bronchus cardiacus disappears 
in whales, and there is only a trace of it in the seal. 
Secretion and Absorption of Gas in the Swimming-bladder and 
Lungs. * — Dr. J. S. Haldane, following up a previous paper, in which he 
gave an account of the evidence which proves that free oxygen, and in 
some cases at least nitrogen, is actively secreted by the epithelium of 
the swimming-bladder, discusses the question whether the exchange of 
gases between the blood and the air present in the alveoli of the lungs 
is also brought about by active secretion or absorption. After stating 
the evidence in favour of the diffusion theory, Dr. Haldane outlines 
some experimental investigations which seem to show that the diffusion 
theory of the respiratory exchange in the lungs is insufficient. The 
majority of these investigations, including those undertaken by himself 
and Dr. Lorrain Smith, go to prove that the lung epithelium participates 
actively in the process of respiratory exchange ; but there are still too 
many discrepancies in the results gained by different observers to admit 
of any certain conclusions being drawn. 
Porus Genitalis in Myxinidse.t — Mr. K. H. Burne has studied this 
in Myxine glutinosa and Bdellostoma cirrhatum , and has done much to 
clear up an obscure point. The main difference between the lampreys 
and Myxinoids lies in the absence in the latter of the direct communi- 
cation between the “ porus genitalis ” and the uro-genital sinus that 
forms so characteristic a feature in the former. The uro-genital sinus 
of lampreys is really absent in the Myxinoids ; and in the latter the anus, 
“ porus genitalis,” and ureters, open into an integumentary cloacal 
chamber, similar to the cloacal chamber common to anus and uro- 
genital sinus in the lamprey. 
Sensitiveness to Light in Amphioxus.t — Herr W. Krause criticises 
Hesse’s recent description of what seemed to him like “ cup-eyes ” on the 
nerve-cord of the lancelet. In 1888, Krause suggested that the animal 
was sensitive all along its spinal cord, and he adheres to this without 
attaching special importance to the grouping of the pigment-granules. 
Similar groupings around the nucleus are common, and may be seen in 
the human epidermis. Krause is inclined to believe that the importance 
of the pigment is not in its disposition, but in its liability to chemical 
change. 
Petromyzont with Large Eyes.§ — Prof. L. Plate gives a prelimi- 
nary account of a Chilian Petromyzont — Maerophthalmia chilensis g. et 
sp. n. — which differs notably from other Cyclostomata in having large 
Teleostean-like eyes. These and its silvery-white colour point to a free 
and active life. 
Relations between Marine Animal and Vegetable Life || — Dr. H. 
M. Vernon has tackled an interesting problem — how the nitrogenous 
matter excreted by marine animals into the water is removed, and what 
* Sci. Progr., ii. (1898) pp. 237-52. 
t Journ. Linn. Soc. (Zool.), xxvi. (1898) pp. 487-95 (1 pi.), j 
j Anat. Anzeig., xiv. (1898) pp. 470-1. 
* § SB. Ges. Nat. Freundc Berlin, 1897, pp. 137-41. 
| || Proc. Boy. Soc., lxiii. (1898) pp. 155-61. 
2 f 2 
