44 



Aquatic ILitt 



rather an absence of the power to expand 

 the chromatophores or color cells. 



On mentioning the condition and later 

 showing specimens to my friend, Pro- 

 fessor T. Brailsford Robertson, he 

 kindly referred me to a series of papers 

 recently published by Dr. P. E. Smith, 

 of the University of California. This 

 author had experimented with frog tad- 

 poles and discovered that if the Hypo- 

 physis cerebri or pituitary bodies were 

 removed, the tadpoles assumed an al- 

 bino condition ; growth was retarded and 

 the larvae were unable to undergo the 

 usual metamorphosis, that is, they were 

 incapable of becoming frogs. It may be 

 said that the experiments were not con- 

 ducted with the aim of producing albin- 

 ism ; this was an unexpected result, but 

 was a condition regarded as of inesti- 

 mable value, as it became an invariable 

 index to the success of the operation of 

 removing the pituitary body. 



The albino tadpoles were next fed 

 with gland substances (pituitary, ad- 

 renal, etc.), and growth was resumed 

 and even exceeded that attained under 

 normal conditions. Another surprising 

 result was the development of pigmented 

 skin, due to the expansion of the chroma- 

 tophores which, though evidently pres- 

 ent, were incapable of action in the ab- 

 sence of the necessary glandular ma- 

 terial. 



It is well known that the absence or 

 derangement of certain bodies, such as 

 the thyroid and pituitary glands, pro- 

 duces strange conditions in the human 

 subject, and the interesting experiments 

 conducted by Dr. Smith fairly conclu- 

 sively prove that albinism in frogs and 

 axolotls is due to some abnormal condi- 

 tion of those apparently insignificant or- 

 gans, of which medical science has much 

 to learn. 



Many animals from man to fishes, 

 down to starfishes at least, are known to 

 produce albinos or color variations, and 



an interesting and valuable field of re- 

 search is thus revealed to students of 

 nature. 



A Metal Net for Larval Fishes 



HARRY W. BALLEISEN 



There are often times when it is advis- 

 able to move recently hatched fishes from 

 one tank to another. When we use a 

 spoon, ladle or cup the fry manage to 

 escape when the implement is raised to 

 the surface, being washed out by the dis- 

 turbance. At this age the fish are very 



tender and are apt to be injured if 

 handled in a cloth net. Hence the metal 

 net as illustrated. 



Take a baking powder can and with 

 tinners' shears cut it down to the depth 

 shown. Select a piece of brass wire- 

 cloth twice the depth of the can in width, 

 and long enough to reach around and 

 slightly over-lap within the can. Before 

 bending the wire-cloth to insert in the 

 can, turn over one long edge, the upper 

 one when completed, then bend the strip 

 (the turned edge outside), and insert in 

 the can and solder ; the screen should ex- 

 tend to the bottom. On the outside of 

 the can solder a short piece of brass 

 tubing, and in it insert a snug-fitting 

 wooden handle. 



The purpose of the wire-cloth is to 

 prevent the fry floating out while the im- 

 plement is being drawn out of the water, 

 while the can retains ample water to 

 insure them against injury. 



