1913] Gee: Bcliavior of Leeches 205 



Bohn (1907) has provided us with a more recent contribution 

 than that of Von Uexkiill. This appeared in the form of a 

 short paper discussing the relation of tropisms, differential sensi- 

 bility, and associations in the behavior of Braiichellion, a leech 

 parasitic on the torpedo. This Branchellion he records as being 

 very strongly positive to light, the intensity of the light deter- 

 mining the degree of random movements previous to orientation. 

 He finds it possible to change the character of the phototactic 

 responses by lack of salt in the water, decapitation, and pro- 

 longed insolation or exjjosure to the sun. In order to explain 

 certain of the reactions of this form, he makes use of '' plicnom- 

 enes associatifs" of a simple type. 



Masterman (1908) discusses the Hirudinea as human para- 

 sites in Palestine. Portions of his paper are of such a significant 

 nature as to warrant quoting in their entirety. "Leeches are 

 common in the fountains and pools of Palestine, particularly in 

 the northern parts known to us familiarly as 'Galilee' and farther 

 north in the district of Lebanon. In the later summer and 

 autumn months they are so plentiful in places that almost every 

 horse and mule passing through these parts has a bleeding mouth. 

 Under such conditions it is not wonderful that human beings 

 from time to time are attacked. . . . Many of the springs in the 

 mountains of Galilee and in Lebanon are widely known for the 

 nuiltitude of leeches which lurk in their waters, but a thirsty 

 traveler seldom has self-control to restrain himself from drinking, 

 and when he does so, particularly at dusk or in the night, he is 

 very likely to suck one in! . . . 



"In tlie eases, some three dozen or so, which I have had 

 under my own observation, the leech has been attached to the 

 epiglottis, the pharynx, the nasal cavities, or, most common of 

 all, the larynx. . . . The haemorrhage, though never great in 

 quantity at any one time, may, when prolonged, be very serious 

 and even fatal. I know of two cases where the patient has 

 actually died from this." The species he gives as Limnatis 

 nilotica. 



Harding (1910) in a paper on the British Leeches, which is 

 primarily a systematic account, includes the habitats and foods, 

 so far as known, of a number of the species. 



