862 



SCIENCE 



[N. S. Vol. XL. No. 1041 



of photographs of the actual specimens. Since 

 these half-tones have not been " touched up " 

 they must prove of the greatest value to stu- 

 dents of Carboniferous plants. 



A USEFUL SOCIETY 



The Sixth Annual Eeport of the " Quebec 

 Society for the Protection of Plants from In- 

 sects and Fungous Diseases " (Quebec, 1914), 

 ■calls attention to a society that must prove to 

 be most useful to the people of the province of 

 Quebec in particular, as well as of all eastern 

 Canada in general. The report itself covers 

 less than a hundred pages, and yet it includes 

 more valuable articles than many much larger 

 reports. Thus among botanical papers there 

 is a short, crisp report of the committee on the 

 flora of the province of Quebec recommending 

 the early publication of a new " Flora of Que- 

 bec"; another on Downy Mildews; still 

 others on Some Plant Diseases of 1913 ; Stor- 

 age Eots of Potatoes and Other Vegetables; 

 A Bacterial Soft Eot of Turnips; Injury and 

 Abscission of Impatiens sultani. One can not 

 help feeling that these Canadians have man- 

 aged to organize a most useful society, for 

 •which they deserve to be congratulated. 



Charles E. Bessey 



The University of Nebraska 



SPECIAL ABTICLES 



the electric motor nerve centers in the 



skates (rajid^) 



While the electric lobes of the brains of 

 torpedos, with their massed motor nerve cells 

 of the electric apparatus, are classic subjects 

 of study, and while the physiologically corre- 

 sponding motor centers of the central nervous 

 system have been described superficially in 

 Malopterurus, Gymnarchus and Gymnotus, 

 the motor nerve apparatus of the other three 

 types of electric fishes (two Teleosts) have 

 never been adequately worked out. The 

 writer has recently worked on this nerve cen- 

 ter of the electric apparatus in the skates 

 with results that promise to be of interest. 



Ewart has already described a motor electric 

 nerve cell from Raja, but it is not certain that 



the cell, which he figures and describes in his 

 short report in the Proc. Royal Soc, Vol. 53, 

 pp. 388-391, is a motor nerve cell belonging 

 to the electric organ or a motor nerve cell be- 

 longing to the muscle that surrounds the elec- 

 tric organ. 



The writer examined the spinal cords of 

 eleven species of skates and found remarkable 

 cells placed in the anterior horn of the cord 

 at various regions which were all opposite the 

 well-known spindle-shaped electric organs 

 found in the tail and lower body of this fish. 

 While these cells were placed thus in the cord 

 among other nerve cells and corresponded in 

 their anterior-posterior distribution with the 

 extent of the electric or^an, yet their cyto- 

 logical character was such that it could 

 scarcely be believed that they were nerve cells 

 at all. They are of unusually large size, irreg- 

 ular in configuration, with many angles and 

 projecting points some of which might be 

 nerve processes. The large cytoplasmic body 

 contains an irregular branching and lobular 

 nucleus containing much chromatin but no 

 definite plasmosome, the opposite condition 

 to that found in most nerve cells. This chro- 

 matin is distributed in the form of numerous 

 (several hundred) masses of considerable size, 

 evenly and regularly strewn through the 

 caryoplasm. 



This type of nucleus is so unusual for a 

 nerve cell that these cells were traced back- 

 ward through a series of embryonic skates to 

 their origin, which proved to be the same as 

 the other motor nerve cells of the anterior 

 horn. Stages were clearly traced that showed 

 them being differentiated from these other 

 cells at an early stage of the embryo within 

 the egg. The physiological activity of these 

 large cells was evidenced by the formation of 

 series of vacuoles which coalesced into larger 

 vacuoles that finally condensed and precipi- 

 tated their contents into a number of heavy, 

 homogeneous granules which were discharged 

 from the cell in a ventral direction and became 

 distributed through and around the tissues of 

 the gray matter. This material appears to be 

 finally absorbed by the blood. Its composition 

 has not yet been determined. 



