1644 SERICULTURE 



still affected but to a less degree an dwith adult trees, the differences obtained 

 were very small. A microscopic examination re\-ealed equal quantities of 

 starch in the leaves of the test plants and of the control plants, and Fehling's 

 solution showed no accumulation of glucose in the treated leaves, so that 

 it may be concluded that the absorbed solution was used up in the develop- 

 ment of the plant. 



IV. An electric bell for giving ivarning of changes of temperature during 

 incubation. — The writer has invented a new instrument to ensure a constant 

 temperature during incubation. It is sensitive to half a degree C, is simple 

 and inexpensive, and may be obtained from Carosi, Rome for 2 lire. 



V. Autumn rearing of silkworms. — Autumn rearing as a whole has 

 not proved a success chiefly owing to the imperfect preparation of the 

 graine. The stripping of mulberry trees in autumn, if properly carried out, 

 need entail none but the very slightest injury to the trees, and where the 

 trees are abundant the supply of leaves should offer no difficulty. 



Some of the methods of obtaining graine for autumn hatching are 

 to be condenmed, i. e. the use of eggs from the previous season or from 

 a very early spring hatching after storage at low temperature during the 

 summer. Other methods jdeld worms of doubtful vigour, as for instance the 

 Quajat method where the graine is prepared in October, estivates during 

 the winter, and hibernates during the summer. Occasional!}' the use of 

 retarded eggs has been recommended before they have been tested tho- 

 roughly under practical conditions (e. g. the retardation of spring eggs by 

 means of electricity, acids, etc.). The best method is undoubtedly that of 

 Dr CrivEi.ti ; it is known as the « enibryostatic » method, and has given 

 excellent results in practice over a number of years. Details of the manage- 

 ment have been kept secret, but in general outline they must resemble 

 that of Martini (given below) as both yield identical results 



Management of silkworms under the Martini system. 



Temperature at which the 



silkworms must be maintained 



"C. 



Period of estivation : 



From laying time to end of August 22 to 27 



During September 20 " 22 



" October 17 " 20 



From November to end of Februar}- 16 " 17 



" March i to 20 8 " 10 



Period of hibernation : 



From March 20 to July 30 2 " 3 



" August I to about August 15 when incubation begins. . gradual rise 



The writer states that 20 years ago he had the ojjportunity of seeing 

 some extensive rearings carried out with graine supplied by Dr Crivelli and 

 even tested the eggs himself. In every case most satisfactory results were 

 oVjtained. Autumn rearing had become po]iularized to the point of being 

 a matter of ctirrent practice in parts of Central Italy, but with the spread 



