1892.] MICROSCOPICAL JOURNAL. 87 



Practical Studies iu Biology. — I. The Potato. 



By H. L. OSBORN, 



HAMLINli, MINN. 



If the reader will obtain a fair, smooth, regularly-formed potato 

 and, after washing its surface thoroughly, examine it carefully, he 

 will be in possession of a yery interesting biological specimen. 

 The surface examination will show^ that, however broad or short 

 or irregular a potato may be, it neyertheless has two ends. At 

 one of these he will find a scar, or, perhaps, a piece of stringy 

 matter which held the potato to the plant from which it grew ; 

 at the other end. a spot known in popular diction as an " eye," 

 surrounded by other eyes. The smaller potatoes are rather more 

 likely to haye these two points at ends of an elongate body than 

 the larger and less symmetrical ones. The surface examination 

 shows more than this ; it shows a thin •' peel " or '■' skin," and at 

 certain regular intervals " eyes." If one now takes a lead pencil 

 and beginning at the bottom or remains of the stem shall trace a 

 line from the lowest eye to the one next above it. going from the 

 rightabout one-third of the way around to tlie second eve, and then 

 going a third further to the third eye, and soon, he will find such 

 a line will wind around and around the potato in the form of a 

 spiral, which will meet every eye in succession at regular inter- 

 vals, and finally terminate on the summit in the apical "eye." 

 In the potato from which this study was made the eyes were 

 numbered in succession from the lowest one, and the full number 

 was 17. The eyes are now seen to be so placed (see figure in 

 the continuation of this paper) that the spiral makes two turns 

 before a second eye is reached, which is directly over a given one, 

 thus four e\'es will invariably be passed over before this eye 

 is reached. Thus the sixth eye is over the first, the seventh over 

 the second, the thirteenth over the eighth and the third. The eyes 

 thus in line are: 1-6-11-16 ; 2-7-1 2-1 7 ; 3-8-13-18; 4-9-14; 

 5-10-15. The fact that the eyes are thus in line is very signifi- 

 cant, and must obviously be the consequence not of any mere 

 chance and unregulated occurrence on their part, but of the 

 operation of some law inherent in the nature of the potato, es- 

 pecially since it is constant for all specimens, and where departed 

 from is obviously due to irregular shape of the potato. It would 

 plainly be no more reasonable to exfoect a potato which was bulged 

 out of all shape to exhibit plainly the symmetry of body natural to 

 potato than to conclude that mankind has but a single eve because 

 we find a few blind men so deformed. 



While the numbers which indicate the arrangement of the 

 buds are constant for all specimens, namely, 5 buds in two turns 

 of the stem, so that buds i, 6, and 11 are in line, etc., it is a very 

 singular fact that in some cases the line connecting them will 

 pass from right to left and in other cases from left to right ; that 

 is to say. some specimens are right-handed, and others are left- 

 handed. 



