204 University of California PiMications in Zoology [Vol. 11 



Bristol (1898) in connection with his -work on the meta- 

 merism of Nephelis includes a few notes on his experience in 

 collecting and keeping leeches which he used in his dissections. 



Graf (1899) in his splendid " Hirudineenstudien " considers, 

 from a comparative point of view principally, the structure and 

 function of the nephridial system of leeches. To a certain extent, 

 also, other features are included, and incidentally some remarks 

 with regard to the feeding reactions of Nephelis. 



Brumpt (1901) treats at considerable length the question of 

 reproduction in the Hirudinea. The structure of the reproduc- 

 tive organs in the various groups of leeches is discussed, as are 

 also the questions of spermatogenesis, ovogenesis, and fertilization. 

 The breeding reactions of several genera are also given. 



Holmes (1905) in his paper on "Random Movements" dis- 

 cusses the general features of phototaxis in Glossiphonia. Some 

 of his comments are as follows: "The method of orientation in 

 these forms is in principle the same as that of the earthworm. 

 When specimens of Glossiphonia are placed in strong light their 

 locomotor reflexes are set in action. In its progress the leech 

 frequently raises the extended anterior part of the body and 

 waves it from side to side as if feeling its way. If the animal 

 turns it in the direction of the strong light it is quickly with- 

 drawn and extended again, usually in another direction. When 

 the leech becomes negatively oriented it may crawl away from 

 the light, like the earthworm, in a nearly straight line. Of a 

 number of random movements in all directions only those are 

 followed up which bring the animal out of the undesirable 

 situation. ' ' 



Von Uexkiill (1905) has explained in a very original and 

 suggestive way and with considerable detail "das Schwimmen," 

 "Verkurzung und Sperrung, " "das Gehen." and "Schleif en- 

 reflex und Umdrehreflex" in the blood-leech. This is by far the 

 most extensive piece of recent work bearing on the behavior of 

 leeches. It considers, however, principally the physiology of the 

 locomotor movements of the blood-leech. The general reactions, 

 such as feeding, responses to contact, light, etc., and the modifi- 

 cations of these, are not included in his study. His views in 

 regard to the locomotor movements are considered in the dis- 

 cussion of those responses in a succeeding portion of this paper. 



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