1891.] Embryology. 59 
Amphioxus.—Prof. E. Ray Lankester and Mr. Arthur Willey 
have a paper on ‘‘ The Development of the Atrial Chamber of Amphi- 
oxus,’’ in the Quar. Jour. for Aug., 1890. Mr. Willey made some 
observations in Sicily on the life of the adult and the embryo which 
are of interest. The adults will spawn in glasses, and this takes place 
about an hour after sundown. The eggs must be distributed into 
glasses containing clean, unfiltered water from the pantano in which 
the adults live. ‘‘If the water is filtered, or if sea-water [outside of 
the pantano] is employed,” the eggs ‘‘ will either die or develop 
abnormally.” Most, if not all, of the ova were discharged through 
the atriopore, which contradicts the statement of NENON, who says 
they issue from the mouth. 
The young larva rests habitually on one side, ug does not bury 
itself in the sand. The larva shows for a time the most marked 
asymmetry, with the mouth on one side and a single row of gill-slits 
on the other. 
The young Amphioxus, after regaining its symmetry, does not lie on 
its side, ‘‘but buries itself upright, tail downwards, with the oral hood , 
alone projecting from the sand.’’ The spawning occurs from April to 
September, inclusive. 
The greater part of the paper is taken up with a description of the 
formation of the atrium and of the organs in the head region. 
The Life-History of the Red Blood-Corpuscles.— Prof. W. 
H. Howell, of the University of Michigan, has a most important and 
interesting paper on the origin of the corpuscles of the blood. 
rather full abstract of this paper is given below, as the subject is one of 
great interest to all students and teachers of physiology, and is either 
treated in a most meagre way, or, worse still, false statements are not 
infrequent in many of our text-books of physiology. Those who care 
for a fuller account will find Dr. Howell’s paper instructive (Zhe 
Journal of Morphology, Vol. IV., No. 1): 
“Before 1869 it was quite generally believed that the red corpuscles 
are formed from the white corpuscles, most. probably while in the cir- 
culation,” but “the evidence is overwhelming against this view. 
In the very young embryo two forms of red corpuscles are found,— 
one large, oval, and always nucleated, resembling the corpuscles of 
the lower vertebrates ; and one small, biconcave, circular in outline, 
and found both nucleated and non-nucleated. The latter are the true 
mammalian corpuscles; the former represent possibly ancestral cor- 
Puscles. The true mammalian corpuscles lose their nuclei by extrusion. 
