ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



1091 



An attacliment (fig. 257) is also supplied for holding other kuives 

 than those specially made for the microtome. It is provided with a 

 slot so that it may be ad- 

 justed ujjon the block, and Fig, 257. 

 with set-screws so that the 

 angle of the cutting edge 

 of the knife may be vai'ied. 

 The knife is fixed by the 

 thumb-screw. It will hold 

 a razor as well as a large 

 knife with handle. 



Seller's Microtome 

 Attacliment. — At the sug- 

 gestion of Dr. C. Seiler 

 the Bausch and Lomb 

 Optical Co. have devised a 



special attachment which may be fastened to either of the preceding 

 microtomes. It consists of a circular V-shaped way which is firmly 

 fixed on the vertical bed. A circular block is fitted to it in a manner 

 similar to that used in the straight movement, and is provided with 

 a grooved slot for the attachment and adjustment of the knife. 

 When the block is made to traverse in the circle the knife moves 

 through the specimen in a circular as well as transverse direction, 

 thus bringing each point of the cutting edge in a continually varying 

 position in contact with the specimen. Dr. Seiler is able to cut 

 large and thin sections in a very satisfactory manner. 



Cambridge Rocking- Microtome.* — Dr. C. 0. Whitman considers 

 that the chief objection to this microtome is, that it is adajited to 

 only one mode of section-cutting, namely, that of producing ribbons 

 of sections imbedded in paraffin. It could not be used fur cutting 

 collodion sections, nor can it be conveniently employed in the Duval- 

 Mason method, where tlie block of paraffin is collodionized before 

 making each section. The position of the object is such that it can- 

 not be conveniently watched during the process of cutting ; and this 

 appears to him to form another serious objection to the instrument. 



Suggestions as to the Preparation and Use of Series of Sections 

 in Zootomical Instruction.f — Prof. R. Eamsay Wright writes on 

 this subject as follows : — It is convenient to have in the laboratory 

 prepared series of certain types, so that the student may supplement 

 tlie information he has acquired from dissection by the study of these. 

 Thus entire seiies of Limax and Cydas and partial series of the 

 earthworiri and leech are almost indispensiblc for an accurate know- 

 ledge of tlie anatomy of these forms. 



Slides 2x3 in. (i. c. double the ordinary width instead of double 

 the ordinary Iciigtli) are most convenient for small stages, and tit into 

 many forms of slide-cabinets. Mica covers may bo cut for these, and 

 have the advantage of cheapness. 



• Araer. Natural,, xix. (ISH.'i) pp. 1022 5. 



t Ibid., pp. niO-20. 



