278 EXPEEIMENT STATION RECORD. [Vor. 37 



tno wcpks in each of the two parts. The animals in the third lot were grazed 

 separately and moved every week to fresh ground or ground not recently 

 gi'azed, but were allowed together at noontime and night, when they were to- 

 gether in a barn with slat floors which was cleaned and disinfected at least 

 once a week. The fourth lot was moved once a week from May to September 

 to fresh pasture and was kept together most of the time, the ewes occasionally 

 being separated from the lambs and grazed on infested pasture when the avail- 

 able fresh pasture was limited. 



At least five lambs from each of the lots were killed and examined in Septem- 

 ber or later, but no material difference was observed in the degree of stomach 

 worm infestation in the various lots. A great reduction in the number of 

 stomach worms present occurred in all of the lots after November 1, as a rule 

 only a comparatively few individual worms being found instead of the usual 

 thousands found in the lambs or ewes examined earlier. 



With reference to hookworms, nodular worms, lungworms, and tapeworms, 

 there was no important difference between the first and second lots. The 

 lambs of the third lot showed hookworms in only one case and then only two 

 specimens. They had few and in some cases no nodular worms or worm 

 nodules, no tapeworms, and no lungworms. The lambs in lot 4 also had com- 

 paratively few hookworms, nodular worms, and worm nodules, only one having 

 lungworms and none tapeworms. 



These experiments apparently indicate that the plan followed as to change 

 of pastures can not be depended upon to control parasitic infestation In lambs, 

 especially in the case of the stomach worm, although, on the other hand, it 

 appeared that a change of pasture every week during the season from May 1 

 to Septt>ml»or 1 kept down the infestation of lambs with hookAvcrrms, nodular 

 worms, lungworms, and tapeworms to a very small amount. It thus appears 

 that these parasites can be more easily controlled than the stomach worm by 

 a sj-stem of pasture rotation. "The probable meaning of the presence of only 

 a few stomach worms in sheep during the winter following a summer in which 

 they were comparatively numerous In other sheep of the same flock is that 

 the average length of life of the adult stomach worm is not more than a few 

 weeks or months; in brief, that the stomach worm is essentially a short-lived 

 parasite." 



The influence of partial thyroidectomy in pigs, C. C. Palmer (.Inier. Jour. 

 Physiol, 42 {1911), No. 4, pp. 572-581, fig. i).— The results of a study by the 

 author at the Veterinary Research Laboratories of the Minnesota Experiment 

 Station show that the extirpation of the main thyroid gland in young pigs 

 does not Induce cretinism, at least within a period of nearly one year. A slight 

 retardation of growth was observed, but the operated pigs otherwise acted 

 similarly to the controls except that they showed a marked lowered resistance 

 to infection. A marked hypertrophy of the accessory thyroid tissue was 

 observed on post-mortem examination of the thyroidectomized pigs. 



It is Indicated that " the main thyroid gland plays an Important part In 

 the normal body resistance to Infection, and when this structure Is removed 

 the accessory thyroids can not completely compensate. In pigs a degree of 

 hypothyroidism not sufficient to lead to marked changes in physical appearance 

 of the animal lowers the resistance to Infection to quite a degree, and Impairs 

 the functions of reproduction." 



Fetal athyrosis. — A study of the iodin requirement of the pregnant sow, 

 G. E. Smith, with the cooperation of H. Welch (Jour. Biol. Chrnx., 29 {1917), 

 No. 2. pp. 215-225). — The authors, at the Montana Experiment Station, have 

 studied the condition of the birth of hairless and otherwise defective pigs 



