1886.] 



MICROSCOPICAL JOURNAL. 



203 



not be distinguished under the micro- 

 scope, either when taken directl}' from 

 the infected organism or from pure cul- 

 tures. We have, then, a close resem- 

 blance in morphological characters 

 and in the more important biological 

 properties, with a few slight but con- 

 stant differences already mentioned 



There is another thought to be pre- 

 sented in this connection which may 

 be of value in the future. It is prob- 

 able that varieties of other germs may 

 arise, either through the effect of long 

 periods of time, in the same localitv, 

 or through changes incident to places 

 far separated from one another. What 

 effect would the ti'ansportation of one 

 variety have upon the severity of an 

 epidemic thereby produced in another 

 locality? May not modification be pro- 

 duced within short periods of time, so 

 that the infection spreading from one 

 centre of disease, after being latent for 

 a time, becomes the cause of a mild or 

 a virulent epidemic ? These questions 

 now need renewed observation with 

 the new light thrown upon them bv 

 the biological study of the disease 

 germs themselves. 



That this view is not new, and that 

 it is looked upon with favor, the fol- 

 lowing extracts from Virchow's re- 

 marks at the Berlin Cholera Confer- 

 ence in the summer of 1SS5 may be 

 of interest : — 



' I have always believed that we 

 should succeed at some time in de- 

 termining that the same bacteria, at 

 different times and under different cir- 

 cumstances, might possess different 



grades of virulence As I am a 



naturalist, I can only put the ques- 

 tion. Does not the changing viru- 

 lence of the causes of disease best 

 explain the difterence in epidemics.'' 

 ....Are there not periods more fa- 

 vorable to the development of the 

 microbe, periods during which it 

 multiplies more vigorously and forms 

 within itself more active substances.?' 



Water Bath for Use in Imbedding. 



The October number of the Amer- 

 ican Naturalist (vol. xx, p. 910) 



contains a description of a water-bath 

 apparatus for paraffin imbedding, of 

 the pattern in use at the Museum 

 Comp. Zool, at Harvard. It is de- 

 scribed bv the author, not with refer- 

 ence to urging its introduction, but 

 for the benefit of any who wish to fit 

 out a laboratory- The bath is a cop- 

 per box 18 cm. long, 9 cm. broad, 

 8 cm. high, with an oven near the 

 bottom for \varming slides ; the oven 

 is without a door. The oven is i cm. 

 high and 12 cm. long, and about i cm. 

 above the bottom of the box. The 

 top of the box is perforated with four 

 small and two large holes, and these are 

 copper-lined wells, three of theiTs 4 cm. 

 deep, one 7 cm. deep. The layer 

 wells are 6 cm. in diameter. They 

 each receive a copper bowl, which fits 

 them nicely, furnished with a bent 

 brass handle upon the side. One is 

 for soft, the other for hard, paraffin. 

 The box is completely closed to the 

 exterior except at two small openings, 

 one forthe introduction of a thermom- 

 eter, the other for the introduction of 

 water. The bath is of small size and 

 is designed to be attached to the work- 

 table of a single student. The ad- 

 vantage of this plan is that each 

 worker of a laborator}' is able to con- 

 trol the heat to suit his particular 

 needs. There is greater expense in 

 this plan for more gas used and the 

 cost of the baths. The bath is sup- 

 ported upon the side of the table and 

 may be readily packed up and trans- 

 ported to the seashoi'e, or other scene 

 of labor. The bath is made by the 

 Educational Supply Company, No. 6 

 Hamilton Place, Boston. Mass., and 

 sells for $6.^0, or with thermometer 

 for $8. 00. "The writer. Dr. Whit- 

 man, mentions in his account a de- 

 vice for suspending the object being 

 imbedded in the paraffin ; it is a coiled 

 wire which is soldered to the margin 

 of the tank and extends down into 

 the cavity, and acts as a shelf on which 

 the object may rest, thus keeping it 

 out of the dirt which is sure to accumu- 

 late near the bottom of the tank. 

 The bath which we have had in 



