ZOOLOGY: R. B. HOWLAND 
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and give me authority to say that in their opinion the changes are in the 
nebula itself. 
The position of the nebula is in a dark lane in the sky, connected 
with the nebulosity around 15 Monocerotis. This seems significant in 
that the two nebulae in which variability has certainly been estabHshed 
both lie in dark regions. These are N.G.C. 1555, known as Hind's 
variable nebula (close to T Tauri), and N.G.C. 6729 in Corona Australis. 
In one other case, that of the planetary N.G.C. 7662, Professor Barnard 
has found that the nucleus varies through several magnitudes. 
Preceding the nucleus (R Monocerotis) by 4!4 and north 97'' is a star 
somewhat fainter than the 15th magnitude with a proper motion of the 
order of 30'' per century. North following 9' and 10', respectively, are 
two variable stars whose maxima are at about 15.5 mag.; and north 
preceding 17' is still another variable with a range of at least from the 
11th to the 17th magnitude; all of which add to the interest of this 
remarkable region of the sky. 
The plates are being measured and a more detailed investigation of the 
data, with reproductions of the photographs, will be published in the 
Astro physical Journal. 
ON THE EFFECT OF REMOVAL OF THE PRONEPHROS OF 
THE AMPHIBIAN EMBRYO 
By Ruth B. Howland 
SWEET BRIAR COLLEGE. SWEET BRIAR. VA. 
Received by the Academy, March 9. 1916 
The following note embodies the results of a series of experiments, 
performed at Yale University at the suggestion of Dr. R. G. Harrison, 
on embryos of the spotted salamander, Amblystoma punctatum. The 
particular problems in mind were first, to determine whether the head 
kidney or pronephros is a functioning organ necessary to the life of the 
embryo, and second, to investigate the correlation of the development 
of this organ with that of other components of the excretory system. 
The embryos used for the experiments were nearly of a uniform age, 
varying slightly in size and degree of development from the condition in 
which the first loop of the pronephric tubules appears as a slight, ventrally 
directed curve of the duct, to the stage in which the two funnels, together 
with the first loop, appear as a broadened Y. (Fig 1.) The tail-bud 
was clearly defined, and the pronephric swelling distinctly visible. In 
all cases, however, embryos were used before contraction of the body 
