Volume 26, Issue 4
October 1947, pages 125-176
pp 125-135 October 1947
A number of routine natural and artificial factors that are likely to affect the values of the refractive index and refractive constant of cow and buffalo milk have been investigated.
Colostrum exhibits a high R.I. and K, both of which reach normal levels in 3 to 5 days after parturition.
Differences in the two constants of milk occur from milking to milking, from day to day and between milks from different quarters of the udder. But the order of variation is unpredictable in every case. The different portions of a milking, however, exhibit a more or less uniform R.I. and a steady rise in the value of K from fore milk to strippings. But in all instances, pooling of the total yield from the animal restores the values to normal limits.
The rainy season, when lush pasture is available for cattle, appears to Cause a marked rise in the limits of R.I. of milk, while the limits of K remain the same all through the year.
Rigorous boiling of milk causes a steady rise in the values of both R.I. and K.
All the data point to the fact that factors which cause a rise in the fat-free solids of milk also increase the measure of the R.I. The refractive constant, on the other hand, remains within normal limits owing to a corresponding change in the density of milk under natural conditions of variation.
pp 136-141 October 1947
Six new hosts ofClaviceps have been recorded and the fungal characters on these hosts are described. These fungi fall into one or the other of the groups previously recorded by Thomaset al. (1945) for the ergots occurring in South India. A slight modification of the grouping adopted by Thomaset al. (1945-1) in classifying the ergots by the conidial characters, has been made. Wild and exotic species of sorghum were infected bySphacelia sorghi.
pp 142-146 October 1947
Phytophthora palmivora Butler was isolated from blighted seedlings ofHibiscus esculentus L. Inoculation experiments proved its pathogenicity. A study of its cultural and sexual behaviour showed that it was a minus strain, not forming oospores in pure culture and forming them only when grown in paired cultures with complementary (plus) strains of the same species.
pp 147-163 October 1947
The formation of oospores in paired cultures of twenty-five isolates ofPhytophthora was studied. These isolates fall into two main groups—the “plus” and the “minus” and the members of one group form oospores when paired with members of the other group. Some of the isolates were found to lose their sexual capacity with continued cultivation on agar media. Fresh isolates form oospores quickly with complementary strains.
pp 164-167 October 1947
pp 168-176 October 1947