926 



SCIENCE 



[N. S. Vol. XXXVIII. No. 



Professor Eoemer, of Marburg, has been 

 called to Greifswald to conduct the hygienic 

 institute as the successor of Professor Loeffler. 



DISCUSSION AND CORBESPONDENCE 



A NEW TYPE OF BACTERIAL DISEASE 



By this title I mean a disease in which the 

 bacterial growth first develops conspicuously as 

 a thick layer on the surface of the plant, and 

 only later penetrates into its interior. 



Eathay's disease of orchard grass (Dactylis 

 glomeraia) described by him in 1899 may be 

 taken as the type of this kind of disease. In 

 1913 I had opportunity to verify Rathay's 

 statements^ on material sent to me from Den- 

 mark by Professor Kc^lpin Ravn, and to make 

 pure cultures and further studies of the organ- 

 ism which in honor of Eathay, may be known 

 as Aplanobacter rdthayi n. sp., with the char- 

 acters assigned to it by Eathay, and in addi- 

 tion the following : 



Nitrates are not reduced; gelatin is finally 

 liquefied, but liquefaction is visible only after 

 some weeks and progresses very slowly ; it does 

 not grow in Cohn's solution ; growth starts off 

 slowly in milk, but is prolonged with forma- 

 tion of a copious chrome yellow precipitate 

 and a wide bright yellow rim; litmus milk is 

 first slowly blued, but becomes purplish after 

 some weeks; it grows so slowly on agar that 

 poured plates which appear to be sterile may 

 eventually give small yellow colonies. Nearly 

 all of Eathay's statements have been found to 

 be correct. This note is here published be- 

 cause of delay in the issue of a longer account. 

 Erwin F. Smith 



the manus of trachodont dinosaurs 

 In a recent article in The Ottawa Naturalist} 

 Mr. Lawrence M. Lambe has described " The 

 Manus in a Specimen of Trachodon from the 

 Edmonton of Alberta," illustrated by three 

 figures. According to Mr. Lambe's interpreta- 

 tion of the Ottawa skeleton the phalangeal 

 formula is as follows : 



1 Site. Ber. Wiener AJcad., 1 Abt.j Bd. CVIII., 

 p. 597. 



1 Vol. XXVII., pp. 21-25, 1913. 



Digit II. with three phalanges, the third bearing 



a hoof. 

 Digit III. with three phalanges, the third bearing 



a hoof. 

 Digit IV. with two phalanges, the second bearing- 



a. hoof. 

 Digit V. with two phalanges, the second bearing 



a hoof. 

 Whereas in a specimen that I have described' 

 the formula is 



Digit II. with three phalanges, the third bearing 

 a hoof. 



Digit III. with three phalanges, the third bearing- 

 a hoof. 



Digit IV. with three phalanges, the third a vesti- 

 gial bone without hoof. 



Digit V. with three phalanges, the third a vesti- 

 gial bone without hoof. 



The writer published a description of the 

 manus of Trachodon annectens,- based on the 

 first reported specimen in which all of the 

 phalanges are present. In this specimen the' 

 full number of phalanges are not only present 

 but each digit is articulated either in the right 

 or the left hand and all are encased in a thin 

 layer of matrix in which the skin impression 

 is preserved. 



In this uncrushed specimen the long slender 

 metacarpals of digits II., III., and IV. are 

 closely appressed as represented in the figure- 

 accompanying the above article, a position veri- 

 fied by structure and by position in three other 

 uncrushed specimens in the American Mu- 

 seum, one in the National Museum, and a sixth 

 in the collection of the Calgary Natural His- 

 tory Society. 



In no specimen of the genus Trachodon 

 known to me have more than two hoof bones 

 been found in the manus — those of digits II. 

 and III. The terminal phalanges of digits 

 IV. and V. are, when uncrushed, rounded bony 

 nodules, very much reduced and were not 

 covered by a hoof or nail. 



If Mr. Lambe's interpretation is correct we 

 have a remarkable specific variation in this 

 genus in which a later species, described by me, 

 has developed an additional phalanx on each 



2 Bull. Am. Mm. Nat. Hist., Vol. XXXI., Art. 

 X., pp. 105-107, 1912. 



