August 2, 1912] 



SCIENCE 



155 



the vexing uncertainties of microtome meth- 

 ods, with which we are all too familiar. 



3. The great saving of time in arriving at 

 results, because of the elimination of the proc- 

 esses involved in imbedding and sectioning the 

 material. 



It may here be stated that a preliminary 

 examination of the pollen mother-cells and of 

 cells secured by needle dissection is greatly 

 aided by the use of a concentrated solution of 

 chloralhydrate, 8 parts of chloralhydrate to 

 5 of distilled water. This is far better for 

 general use than phenol, eau-de-Javelle and 

 similar clarifying reagents. It will enable the 

 worker to tell at once if the cells under ob- 

 servation are in that particular stage of karyo- 

 kinesis that it is desired to secure, as the 

 spindles and chromosomes are rendered suffi- 

 ciently visible to determine the mitotic stage. 

 The regular treatment above described can 

 then be carried out. 



The writer would be thankful to hear from 

 any members of the society who, upon investi- 

 gating the foregoing suggestions, have adverse 

 criticisms to offer or suggestions of improve- 

 ment to make.' 



Albert Mann 



Office op Ageicultural Technology, 

 U. S. Depaetment of Agriculture, 

 Washington, D. C, 

 December 15, 1911 



of apples was begun at the Virginia Experi- 

 ment Station under the direction of Dr. H. S. 

 Reed. Four distinctly different types of Ph. 

 piriiia were isolated from leaves collected at 

 Blacksburg, Va., by the poured plate method. 

 The different types are possibly elementary 

 species in the De Vriesian sense of the term 

 or pure lines according to Johannsen's use of 

 the term, but will be called strains in this 

 preliminary report. 



Microscopically there is much similarity in 

 these strains, except in Nos. 1 and 4 where 

 chlamydospores are produced. The conidia of 

 all four are identical in all characters and 

 the mycelium of only one can be told from 

 the others. The conidia are one-celled, ellip- 

 tical, hyaline, sometimes with two oil drops. 

 When grovm on the same medium no differ- 

 ence in size is noted. On apple leaf agar these 

 spores measure on the average 2.2 X ^.8 mi- 

 crons. The manner of pycnidia and conidia 

 production is the same with all strains. 



The macroscopic characters are quite dif- 

 ferent and any strain may be easily recog- 

 nized in pure culture. For the sake of con- 

 venience these strains have been numbered 1, 

 2, 3 and 4. So far they have been grown on 

 only three media, viz., apple leaf agar, apple 

 fruit agar and synthetic agar made accord- 

 ing to the following formula: 



results of pure culture studies on phyl- 

 losticta pirina sacc' 

 In the summer of 1911 a study of Phyllos- 

 iicta in connection with the frog-eye leaf spot 



' Before presenting the above paper I tried to 

 find if a description of this method had been pre- 

 viously published, but could find no trace of it. 

 Since the meeting of the association I find that 

 Professor E. H. Campbell describes a similar proc- 

 ess in Bull. Torrey Bot. Club, Vol. 17, p. 117. 

 As, however, Professor Campbell 's article does not 

 agree in technic with my own, and as it is also 

 •evident that this desirable process is not widely 

 used, I think it desirable to publish the paper 

 together with this reference. 



' Paper No. 17 from Laboratory of Plant Pathol- 

 •ogy, Virginia Agricultural Experiment Station. 



NH^NOs 10.0 



K.HPO, 5.0 g. 



MgSOs 2.5 g. 



Cane sugar 50.0 g. 



Agar agar 20.0 g, 



H,0 1,000 



Descriptions of test-tube cultures of these 

 four strains of Ph. pirina on the three media 

 used and some microscopic features follow: 



STRAIN NO. 1 



Apple Leaf Agar. — Growth diffuse; myce- 

 lium brownish in mass; aerial hyphse short, 

 snow white, sparse except at top and sides of 

 slant or sometimes in patches on surface of 

 culture; pycnidia small, very dark brown to 



