REACTION OF SELACHII TO INJECTIONS 125 



averaged only 0.25 cc. in six hours, or at the rate of 1 cc. a day. 

 The excretion is alkaline to litmus. It is clear, but contains 

 bits of mucus. The amount of this excretion is not copious, but 

 the entire amount produced by both kidneys is only a little over 

 20 cc. in twenty-four hours. Since the size of the digitiform 

 gland is much less than one-twentieth of that of the kidneys, its 

 excretion is relatively greater than the amount of urine given off. 

 Crawford ('99) obtained urea from the digitiform gland and sug- 

 gested the possibility of excretory function for this organ. 

 Hyrtl ('58) regarded it as an accessory sex gland, and Blanchard 

 ('82) stated that it is potentially able to aid digestion because an 

 extract of it splits starch and emulsifies fat. An extract is, how- 

 ever, not the same thing as a secretion and hence Blanchard's 

 conclusion may not be correct. It should be borne in mind that 

 the product from the gland is discharged into the intestine just 

 above the cloaca at a place where digestion has doubtless ceased. 

 Morgera ('16) thought that the digitiform gland has an internal 

 secretion which causes the intestines to contract, thus aiding in 

 the passage of substances through the gut, because he found 

 that passage of food through the intestine was checked by extir- 

 pation of the gland and restored by the injection of an extract of 

 it. One must consider that the interference with the passage of 

 food in these experiments may have been but a temporary dis- 

 turbance from the operation, that would have disappeared later. 

 Also, as stated above a glandular extract is not the same thing 

 as a normal secretion of the gland. 



Cushny ('17) believes that urine is excreted by glomeruli 

 and not by the renal tubules. If the secretion of the digiti- 

 form gland is a true excretion, then the renal tubules may also 

 be able to excrete, in which case, Cushny's theory is incorrect. 



We were able to recover in the excretion from the digitiform 

 gland after injection into the animal two solutions, namely, 

 potassium iodide and pthalein, but not any of the others used. 

 The other solutions if present were too dilute to be demon- 

 strated. Weed's solution passed into the cells of the tubules, 

 as shown microscopically, only in small amounts, although it 

 was present in the blood-vessels in relatively concentrated form. 



