308 



" filosite." In this case the few sprouts produced become con- 

 siderably elongated, remain very slender, and usually do not 

 appear above ground, and when they do so, produce only a few 

 small stunted leaves. Here again there was an absence of disease, 

 and the author considers that " filosite " is due to decadence and 

 loss of vitality, brought about by the employment of the vegetative 

 method of reproduction invariably followed. In those countries 

 where attention is paid to the production of improved varieties of 

 potatoes, certain points have been constantly kept in view. 

 Amongst such may be enumerated : increase of crop ; improved 

 flavour ; smooth and even surface ; immunity from disease. 

 With the first three points cultivators have surpassed their most 

 sanguine expectations, and it is hoped that by a strict application 

 of Mendelian laws, a strain of potatoes immune to all ills will 

 shortly be forthcoming. 



Unfortunately the method of selection and the lines followed 



111 r>rn<lnf>infr tViaaa »>->n/»V. r)^«!».^^l i™..~ x~ ;„ __x.x~.-.. 'U„-»r^ 



improvements 



modifications 



which have resulted in sterility or the failure to form sprouts by 

 the tubers. This failure has been shown, by a series of experi- 

 ments conducted at Kew and extending over three years, to be 

 accompanied by a combination of two distinct specific conditions : 

 i., more or less arrest of the development of the vascular system 

 of the tuber ; ii., comparative absence of the ferment or enzyme 

 called diastase from the tuber. 



A tuber, as is well-known, is the very much swollen terminal 

 portion of an underground branch specialised for the purpose of 

 a vegetative method of reproduction. Such tubers retain, under 

 normal conditions, those structures present in the above-ground 

 stem of a potato plant. The main bulk of a tuber consists of a 

 mass of tissue crowded with starch, which is used up in the 

 tormation of new shoots or sprouts. This starch is conveyed to 

 tne growing shoots through certain portions of the fibro-vascular 

 8} stem, which appears to the naked eye, when a tuber is cut across, 

 f a thin line forming a ring situated some little distance from the 

 surtace ot the tuber. Branches from this ring pass outwards to the 

 eyes or sunken points from which the sprouts originate. Now 



^Tf° Vement l n , the tubers > from the culinary standpoint, 

 w£ I ^suited from these methods of selection and inter- 



Zl„? g >- *t th , e same time been accompanied by a serious 



v e 2 ratl ™°£ the fibro-vascular system f in fact, in many 



ff IS Y ? been examin ed microscopically, this system 



is touna to be so much reduced, especially in the branches con- 



ae mam ring with the « eyes,' as to be rendered incapable 



trim? the riPPPaao^Tr o™, *i. „c !• .i i- ,1 , i„ AiL. 



necting the 



nf nniZrcZ' +C s ne 'eyes,' as to be rendered incapable 



»rnSrS D V * ecessar 7 amount of food from the tuber to the 

 Svlwrf? 1; Gom ^^h the growing shoots are either not 

 vitm S ' ° r .°? iy devel °ped as weakly branches devoid of 

 ofa centnrv P + enshm S- Ifc » a well-known fact that a quarter 

 tlrthSJ^l^? * ed P° tatoes (even the varieties most renowned 

 inflavL.^?? 7 ° r \ fl ° Ury ' V^***) were apt to become sweet 

 earlvI u rTn^ r ^ an( \r Iln8uitable for table Ptoses during the 

 foi nrevZi ^- h ^ 7 arious methods of treatment were devised 

 "d^KHv W B deteriora tion from a culinary standpoint, more 

 specially m the case of potatoes stored on board ship for use 





