232 bulletin: museum of comparative zoology. 



In Figure 14 (Plate 3) several structures are shown in which the 

 neurofibrillae could be distinguished. As a rule, these appear to be 

 independent of one another, and to take more or less parallel courses. 

 In some preparations, however, the neurofibrillae appear to form a 

 terminal basket work. Examples of this are shown in Figures 21, 

 22, 26 (Plate 4). Whether this structure is in reality a basket work, 

 formed by the interlacing of neurofibrillae, or a structure formed by 

 the anastomosis of neurofibrillae, is a question which I cannot now 

 answer. I know of no way to settle such a question except by careful 

 focusing, and in this case the diameter of the neurofibrillae is too small 

 to permit of answering the question by that method. Such structures 

 are rarely seen in my preparations, there being only two sections in 

 which I have observed them. When I first noticed them I was in- 

 clined to regard them as the equivalent of the structures described by 

 Kolmer under the name of pericellular networks. By comparing the 

 sections in which these structures occurred, however, with the adjacent 

 sections in the series, I came to the conclusion that they were incom- 

 plete parts of larger terminal structures, the main bodies of which lay 

 in the next section, and that they had been obtained by cutting thin 

 slices from the surfaces of these structures. 



The terminal expansions which have been designated as "Kelch- 

 bildungen" may be regarded as a type of free termination, if I am 

 correct in my belief that they are related to the sense cells only by 

 contact, and that no nervous structures occur within the sense cells. 

 They are so characteristic in their form, however, that it seems wise 

 to class them in a category by themselves. Their expansions are 

 chiefly horizontal, as in Figures 12, 14 (Plate 3); but may tend toward 

 the vertical, as in Figures 11, 16 (Plate 3). 



There is not a pronounced condition of secondary branching, such 

 as exists in the terminal structures of the maculae. Such branches as 

 are given off are much shorter than those of the maculae, and do not 

 penetrate far between the sense cells. The sense cells, rather, rest 

 upon the nervous material of the calyx, or are slightly imbedded in it. 



There is another type of free termination in the cristae, which difters 

 widely from the form just described, and corresponds more closely to 

 what is generally understood by free terminations, in that the terminal 

 twigs penetrate farther into the stratum of the sensory epithelium. 

 In some cases they may be traced to fine fibres in the eighth nerve, 

 which, after penetrating the basement membrane, make their way to 

 their terminations between the sense cells. Examples of such fine 

 fibres, which end free without branching, are represented in Figures 



