and Laboratory Methods. '-^159 



I think it may be not without interest to quote from Prof. His, for nothing 

 could better illustrate how much we have progressed since ISTC than his own 

 statement of the advantages of his instrument. He says, " I have used the 

 instrument since 18G() and have prepared during this epoch over 5000 sections, 

 (5000 sections in four years ! Students often prepare as many now in a single 

 day). Without this apparatus I might have been able, like others undoubtedly, to 

 prepare many a fine section, but certainly not such a large number. I have 

 thus gained in time and also saved material; but what is more important than 

 this, and in itself a very important gain, I consider to be the fact that this instru- 

 ment has permitted a precision of work which would never have been possible 

 with hand sections. It has rendered it possible for me to obtain uninterrupted 

 series of sections of the object to be investigated. To obtain plastic conceptions 

 from pictures of sections is unquestionably a round-about and fatiguing way to 

 the end desired, but we cannot escape it. The objects are too small for us to 

 observe their plastic form directly. Everyone may easily experience how impor- 

 tant the uninterrupted series of sections may be for such reconstructions, or 

 plastic views, if he will take the trouble to reproduce his formed conceptions in 

 wax or clay. Thus the new microtome has become entirely indispensable to me 

 in embryological investigations. Another object for which it has shown itself 

 very useful is the retina, and I may call attention to the fact that with the help 

 of this apparatus one may determine very exactly the typography of the yellovif 

 spot. Perhaps it may also show itself very useful in many an investigation of 

 small animals. On the other hand, I should not estimate its importance for the 

 investigation of large organs so highly." 



This instrument was manufactured by the Socirtr Genevoise pour la construc- 

 tion d' instruments dc p/tysiquc. Those who are sufificiently acquainted with the 

 history of embryology to appreciate the great value of Prof. His's monograph on 

 the Development of the Chick, and of his many other papers, will be quick to 

 recognize that this microtome proved its value by the results which it helped to 

 secure. Prof. His's microtome, however, did not come into very general use. 

 This was perhaps chiefly due to the introduction of another microtome by Prof. 

 Leon Ranvier, a microtome on the same general principle, but much simpler in 

 construction and more convenient in use. 



The device in question was, so far as I am aware, first described 

 in the French edition of Frey's Histology, prepared by Ranvier, 

 page 712, and was afterwards described and figured in the first 

 edition of Ranvier's Traitc Technique D' Histologic, page 40. This 

 microtome consists of a tube of brass with a flange-like plate at its 

 top and a micrometer screw at the bottom (Fig. 3). The plate serves 

 to guide the knife, and the object to be cut is placed in the tube 

 and is raised by turning the microtome screw. In Ranvier's labo- ^ 



ratory this little apparatus was much used. The practice was to j^^jj^jgj.g 

 embed the object to be cut in elderpith, which was then pressed into Microtome, 

 the tube of the microtome ; the pith when moistened with alcohol 

 swells a little ; and if the operation is carried out with care and skill the 

 object will be held sufficiently firm for cutting purposes. The instrument 



