1884.] 



MICROSCOPICAL JOURNAL. 



37 



investigated, and now it must be ad- 

 mitted that a very considerable pro- 

 portion of our pork is trichinous ; 

 what proportion we cannot state, but 

 it is just as well not to eat very much 

 pork before it is cooked. 



There is another side to this mat- 

 ter, however, as concents the legisla- 

 tion in foreign lands. Although cases 

 of trichinaisis occur from time to time 

 in France, and particularly in German 

 countries, not one single case, so far 

 as we are aware, has been traced to 

 the use of American pork. There is 

 very strong probability, if we cannot 

 say absolute certainty, that the salting 

 kills the worms, so that they are harm- 

 less by the time they arrive across the 

 water. 



Cutting Sections in Ribbons. — 

 The process of cutting sections in 

 ribbons, recently introduced, is much 

 employed in the laboratory of the 

 Johns Hopkins University, where we 

 had the pleasure of witnessing the op- 

 eration. We are indebted to Prof. 

 VV. K. Brooks for kindly illustrating 

 the process and some of its results. 



The object of the process- is to en- 

 able the observer to cut a series of ex- 

 tremely thin sections of any soft prep- 

 aration, such as an embryo for exam- 

 ple, and to mount the sections in a 

 series in the order of succession, re- 

 taining all the parts of the specimen 

 in their proper position. The value 

 of the process needs no further expla- 

 nation. It is carried out perfectly, 

 and in an exceedingly simple manner. 



The specimen is first properly pre- 

 pared, and imbedded in paraffin. The 

 paraffin is then placed in the section 

 cutter, which is made on the princi- 

 ple of the Rivet microtome, although 

 much longer than the usual form of 

 the latter instrument, and somewhat 

 modified in the details of construction. 

 Sections are then rapidly cut, by mov- 

 ing the knife forward and backward 

 within proper limits, and the succes- 

 sive sections of paraffin, which are 

 square, adhere together by their edges 

 into a ribbon, which may grow to an 



indefinite length. It is essential that 

 the paraffin be of the proper consist- 

 ency and at the right temperature. 



Slides are now prepared by spread- 

 ing a thin layer of shellac dissolved 

 in creosote on one surface, to which 

 the ribbons are now transferred, two 

 or three being placed parallel on each 

 slide so that the sections may be read- 

 ily examined in succession. By heat- 

 ing for a short time in a warm oven 

 the sections become firmly attached to 

 the slide, and may be mounted in bal- 

 sam with very little trouble. As a 

 result of this method of procedure we 

 were shown a series of sections across 

 the body of Lingula^ in which the 

 arms were shown in section precisely 

 as in life, and in the stomach were re- 

 mains of diatoms quite undisturbed 

 by the operations of preparation. 



NOTES. 



— Dr. F. M. Hamlin advises the use of 

 crimson lake as a color for the ground of 

 opaque mounts. When the object is 

 white he considers this better than a black 

 ground, but for objects of different colors 

 he selects a ground which seems to show 

 them best. 



— We have been much interested in the 

 account by Prof John M. Coulter of the 

 development of a dandelion flower, which 

 was read at the Minneapolis meeting of 

 the A. A. A. S., and has now been pub- 

 lished with illustrations. It is a very well- 

 written and instructive article, especially 

 for botanists. 



— Dr. Allen Y. Moore has sent us a 

 slide of Amphipleura peUucida, prepared 

 by himself in a mounting medium, which 

 he states has an index of refraction of 

 2.30. We have not yet been able to ex- 

 amine the diatom with sufficient care to 

 justify any extended notice at this time, 

 but we can say the appearance of the frus- 

 tule is quite remarkable. It can be dis- 

 tinctly seen under a low-power objective 

 under circumstances that a specimen in 

 balsam would be quite invisible. Dr. 

 Moore states he has "had no difficulty 

 in seeing the dots on the valves with my 

 Spencer^ n. a. 1.35, with Beck's ver- 

 tical illuminator, using lamplight." 



— The Rev. Fayette Hurd, who has long 

 been working on the problem of produc- 



