2020 Journal of Applied Microscopy 



matic (blue) light was used, and very good results were obtained with Gifford's 

 malachite green screen. 



Ordinary methods of fixing and staining are of no avail in the preparation of 

 Trypanosoma. Blood films must be made as thin and even as possible. This 

 was accomplished by placing a drop of the affected blood on a corner of a cover- 

 glass and spreading it with a piece of goldbeater's skin with straight edge and a 

 width a little less than the cover-glass. Fixation by the vapor from a mixture 

 of equal parts of glacial acetic acid and 2 per cent, osmic acid gave the finest 

 results. Good results for general work were obtained with GuUand's mixture 

 (absolute alcohol 10 parts, formalin 90 parts) allowed to act five or ten minutes, 

 after which the specimen should be washed in running water and dried before 

 staining. The only stain which proved to be of value is a modification of 

 Romanowsky's mixture, prepared as follows : A 1 per cent, solution of methylen 

 blue med. pur. (Hochst) is made in distilled water and .5 per cent, of potassium 

 carbonate is added. The mixture is then incubated at 37° for forty-eight 

 hours and filtered when cold. Instead of eosin the more uniform and constant 

 erythrosin was employed. A .001 per cent, solution is made, and .25 per cent, 

 formalin added to prevent the growth of moulds. The solutions are mixed for 

 use as follows: 20 cm^ of distilled water are placed in each of two beakers. 

 To one of these 6 or 8 drops of the methylen blue solution are added and to the 

 other 20 drops of the erythrosin solution. The two are quickly mixed and poured 

 in a flat dish in which the preparations have been placed for staining. This is 

 accomplished in 20 minutes. The preparations are then washed in distilled 

 water till no more color comes away, and dried in the air without heat, and 

 mounted in turpentine colophonium. 



The organism appears in the blood of the rat and mouse forty-eight hours 

 after inoculation. The spleen becomes greatly enlarged and contains plasmodial 

 material, some amoeboid forms, and a few adult flagellated stages. The blood 

 from the lungs contains many amoeboid stages, but few plasmodia or adults. 

 The glands contain many amoeboid forms and a fair quantity of adults. Only 

 the liver, kidneys, and bone-marrow contain adults in quantity corresponding 

 with those in the blood. At death the cerebral capillaries are blocked with 

 amoeboid stages. Different hosts exhibit different degrees of resistance to the 

 parasite and its occurrence and distribution vary greatly, as does also the 

 relative development of the different stages. Infection is fatal, killing rats in 

 five days, while guinea pigs live for eighteen weeks. Phagocytosis of amoeboid 

 stages was frequently observed. Removal of the spleen decreases this activity 

 and hastens the fatal termination. c. a. k. 



The embryos of this scorpion-spider were 



Gough, L. H. The Development of ^./w^/«j secured at Para. Methods of fixation 

 piimilio, Koch : a Contribution to the 



Embryology of the Pedipalps. Quart. and preservation are not given. Diffi- 

 Journ. Mic. Sci. 45 : 595-631, pis. 32, ^Z^ culties in sectioning caused by the yolk 



were overcome by the colloidin-paraffin 

 method as follows : The eggs were graded gradually to absolute alcohol and 

 placed in celloidin for a number of days, then passed into chloroform and from 

 this to paraffin and were then treated as ordinary paraffin objects. The sections 

 were arranged on the slide by the water method, the water removed by blotting 

 paper and then celloidin poured on the sections. This prevents shrinkage of 

 the egg envelope or crumbling of the yolk in subsequent treatment of the slides 

 in staining and mounting. The paraffin was removed by chloroform. Sections 

 were stained in haematoxlyn-eosin. c. a. k. 



