128 



THE ART OF MAKING MICROSCOPE SLIDES T. S. intestine 



Table 3 — (Continued) 



Defect 



Cause 



Remedy 



Method of Prevention 



2. Long storage in 

 formaldehyde 



2. None 



2. Never store tissues 

 in formaldehyde — 

 always in paraffin 

 blocks 



is not }et ready. If, however, the removal 

 of the dried balsam leaves no sticky resi- 

 due, it is necessary to provide two finger 

 bowls: one of 90% alcohol and the second 

 of a moderately strong solution of soap 

 and water. The whole slide is then dipped 

 in the 90% alcohol and rubbed briskh' 

 until the excess balsam is I'emoved. It is 

 immediately (to avoid softening the bal- 

 sam) rinsed in the soap solution, and then 

 polished. 



If the slides are unsatisfactory, tables 2 

 and 3 above may help to locate the trouble. 



When dealing with valuable series of 

 sections it is ahvays as w'ell to write the 

 serial numl^er of the slide, and some indi- 

 cation of its nature, on the glass in dia- 

 mond before attaching the label. Labels 

 are constantly becoming detached from 

 sUdes and it is well to have a permanent 

 record underneath them. It has already 

 been pointed out that no two people agree 

 as to what label adhesive to use. The 

 author would only reiterate the counsel he 

 has given in previous chapters: that both 



sides of the label be licked thoroughly, 

 that it then be pressed into position on the 

 slide, allowed to dry slowdy, and the requi- 

 site information written with waterproof 

 India ink. 



The violent objections which the author 

 has expressed in previous chapters to stor- 

 ing wholemounts in vertical grooved filing 

 cabinets, do not, of course, apply to sec- 

 tions, since the section is attached to the 

 slide and cannot drift through the mount- 

 ant. Storing in grooved trays, which hold 

 the shde vertically, is undoubtedly the 

 simplest method of storing such sections, 

 but much space can be saved if they are 

 placed in pouches of ordinary indexing 

 cards. If two 5 by 3 index cards be taken, 

 and one be cut down to 5 by 2, the smaller 

 may then be stapled to the first card in 

 such a manner as to leave a pocket into 

 which a slide may be inserted. The full 

 data may then be written on the index 

 card, and these tw^o-card pockets bearing 

 the slides can be accumulated in ordinary 

 card-file drawers. 



Typical Examples 



The Preparation of a Transverse Section of the Small Intestine of the 



Frog Stained with Hematoxylin-eosin 



This is the simi)lest exam]:)le of paraffin 

 sectioning which can be imagined, and it 

 may well serve as an introduction to this 

 type of technique, either for a class or for 

 an individual. The intestine of a fi'og has 

 been selected, owing to tlie usual avail- 

 abiUty of this form in laboratories; but 

 any small animal may be substituted in its 

 place. 



Before killing the frog it is necessary to 

 have on hand a selected fixative and, since 

 this is intended to be an example of the ut- 



most simplicity, it is suggested that the 

 cupric-nitric-paranitrophenol mixture of 

 Petrunkewitsch (Chapter 18 F 4900.0040 

 Petrunkewitsch 1933) be employed. This 

 fixative is entirely foolproof: objects may 

 remain in it for weeks without damage, 

 and it also permits excellent afterstaining 

 by almost any known technique. If only a 

 piece of intestine is to be fixed, 100 milli- 

 liters of fixative will be sufficient; but 

 there is no reason why any other organ in 

 the animal (with the exception of the cen- 



