88 the microscope. June, 



the excessive proportion of water (some 92 per cent.) in the 

 fresh turnip, which is so obvious when it is cooked for food, 

 may further account for the exceptionally empiy appearance 

 of these cells. 



There are a few wretched fibro-vascular bundles sprawling 

 through it at the extraordinary intervals of two or three mm. 

 apart, the fibres which would commonly suffice for a small 

 fibrous root being here almost lost in an enormous overgrowth 

 of pith-like tissue. One of the bundles happens to be cut 

 longitudinally for some distance, giving pretty glimpses of rec- 

 ticulated vessels. 



This monotonous mass gives a key to one of the most ex- 

 treme instances known to economic botany, of specialization 

 produced by cultivation. 



The turnips (Brassica campestris,L.), including the Swedish 

 turnips, or rutabagas, must have been originally weedy plants 

 of the cruciferous (mustard) family, and one variety of the 

 same species (?); colza, or rape seed, still remains near the 

 wild state, with a small annual root, after much cultivation for 

 its oily seeds. They are most nearly related to the slender 

 mustards, of pungent seeds, and to the overgrown cabbages 

 which, like themselves, mostly run to an excessive storing of 

 food, but in the leaves instead of the stem — only one of them, 

 the kohlrabi, storing no small part in a turnip-like thickening 

 of its clumsy stem. All these forms must have diverged from 

 a common type, at no very distant time, geologically speak- 

 ing, and their assignment to (our) varieties, species, and even 

 genera, is necessarily uncertain, changeable and unsatisfac- 

 tory. 



The " turnip " or u turnip-root " of the gardeners is a com- 

 bination, the bottom being evidently root, and the top as 

 plainly stem, but both are so deformed into a simple lump of 

 stored food, that it is often impossible to see, with or without 

 the microscope, where one ends and the other begins. Prob- 

 ably no one could say, from this specimen, whether it was 

 root or stem. It is, both histologically and mechanically, as 

 poorly adapted to either as is compatible with keeping the 

 plant together for a year and a-half. Beyond this limit every- 

 thing is sacrificed to the rapid and economical storing of food. 

 Nor is it any longer a storing for next summer's use of the 

 plant, in p-oducing a vast crop of flowers and seeds, for the 

 development has been forced by cultivation to a degree far 

 beyond that which is useful or sife for the plant even under 

 the most favorable natural conditions ; but to the farmer, in- 

 stead, when protected by his fostering care, it furnishes a 

 greater amount of food for man and beast than can begot from 



