164 T. H. Morgan. 



this gland, as well as the prostate, was removed no young at all 

 were born, although frequent union with the females took place. 

 The results may be due to the semen being insufficiently diluted 

 when it is not mixed with the secretions of the glands, or else to 

 the absence of proper excitation of the spermatozoa when the 

 gland-secretion is removed. That the spermatozoa may be nor- 

 mally acted upon by the secretion of the glands was shown by 

 Steinach in the following way: Sperm from the vas deferens was 

 mixed with a physiological salt-solution. A drop was placed 

 under a cover slip and the edges sealed to prevent evaporation. 

 The preparation was kept at a temperature of 35° to 37° C. A 

 similar preparation was made with the secretion of the prostate. 

 In the former the spermatozoa began to lose their activity in one 

 and a half hours, and after three hours had come completely 

 to rest. In the other preparation, that containing the extract 

 from the prostate gland, the spermatozoa were active after 1 1 

 hours, and ceased to move altogether only after 22 hours. This 

 experiment shows that the secretion of the gland prolongs greatly 

 the period of activity of the spermatozoa. Whether it excites 

 them to greater activity is not stated, but Kolliker's results leave 

 no doubt on this score. The decrease in the fertilizing power 

 when the glands were removed may well be connected, as sug- 

 gested above, with the lessened activity of the spermatozoa. 



Duller has recently studied the question as^ to whether the 

 spermatozoa of the sea urchin are attracted to the egg, — in other 

 words, whether, as some authors have assumed off-hand to be the 

 case, there is a chemotactic action of the egg on the spermatozoa. 

 He points out that although Strasburger claimed that the egg 

 of Fucus excretes a substance that attracts the spermatozoon from 

 a distance of two diameters of the egg, Bordet and Buller himself 

 have failed to confirm this statement. Massart thinks that In 

 the case of the frog the meeting of the spermatozoon and the egg 

 Is purely accidental. Buller finds for the sea-urchins, Arbacia, 

 Echinus, and others, that when the spermatozoa are set free near 

 the egg they show no tendency to swim towards it. The dense 

 collection of spermatozoa that forms around the egg is due to 

 those that happened to run into the jelly sticking there. These 



