230 THE AMERICAN MONTHLY [July 



be produced by an org"anism of the nature of a bacillus 

 embedded in mucilag'e, and very closely resemblintr B. 

 cuboniana, a parasite of the mulberry. In Bulletin, No. 12, 

 for 1896, of the Division of Veg-etable Physiolog-y of the U. 

 S. Department of Ag-riculture, Mr. E. F. Smith states 

 that several species of Solanacea^ — the potato, tomato, and 

 eg-g^-plant, Solarium melong-ena, — are attacked by a disease 

 which he calls "brown rot," due toa hitherto undescribed 

 parasite, which he names Bacillus solanacearum. It closely 

 resembles B. tracheiphilus and the form known as "Kra- 

 mer's bacillus," but differs in several characters from 

 both. In the Revue Mycolog^ique for 1896 M. E. Roze has 

 described several bacteria which cause diseases in the cul- 

 tivated potato, viz., Micrococcus nuclei, imperatoris, pellu- 

 cidus, albidus, and flavidus. He says that M. pellucidus 

 is alwavs found associated with the "scab." 



BIOLOGICAL NOTES. 



Size of Stained Blood-Corpuscles.- — My experience has 

 been that human blood, or any non-nucleated blood, appears 

 best when unstained. It may be an optical illusion, but I 

 cannot escape the conclusion that stainino- reduces, in 

 some manner, the size of the corpuscles. 



When stained on the slide by the process of Dr. Moore, 

 as these corpuscles were, there is no chang-e of size pro- 

 duced by the staining-. The coag-ulable matter of the 

 blood and of the corpuscles becomes fixed, so to speak, by 

 the drying- process, and while permeable to aqueous fluids 

 does not swell up, nor does it, on the subsequent drying-, 

 contract beyond its orig-inal dimensions when first dried. 

 I have tested this by many measurements, and while there 

 is sometimes a minute variance in the measurements, it 

 is no greater than ordinarily occurs in successive meas- 

 urements of the same corpuscle, stained or uustained. 

 Dr. Moore tested this by measuring- dry corpuscles, then 

 staining- them and remeasuring- the same corpuscles which 

 were identified by their relation to certain marks on the 

 slide. I have slides of blood, spread at a single sweep and 



