ANIMAL PEODUCTION. 75 



cause for partial or complete sterility in the fowl it was found tbat "birds 

 whicli are hereditarily high layers may fail to make good performance records 

 because for some anatomical reason it is impossible for yolks to enter the 

 oviduct. Birds which ovulate, or return partly formed eggs, into the body 

 cavity usually show the nesting instinct. The nesting records show a rhythm 

 similar to egg records of normal birds and it seems probable that they are 

 the normal resultant of the ovulation." 



It is stated that " in case of stoppage of the duct at any level the duct on 

 both sides of the point of stoppage passes through the same cyclic changes co- 

 ordinated with the cyclic changes in the ovary as a normal unobstructed duct. 

 The duct functions only as far as it receives the stimulus of the advancing egg. 

 Absence of iiressure from the funnel does not prevent or apparently greatly 

 retard ovulation. Increased internal pressure may therefore be the most 

 important factor in normal ovulation. Yolks of partly or fully formed eggs 

 may be absorbed rapidly and in large numbers from the peritoneal surface 

 without causing any serious derangement of normal metabolic processes." 



Some physiolog'ical observations regarding plumage patterns, R. Pearl 

 and Alice M. Boring {Science, n. ser., 39 {191 Ji), No. 995, pp. l-'/.i, 1.^; al)s. in 

 Maine 8ta. Bui. 234 {1914), pp. 2S1-2S3). — A study was made of the plumage 

 pattern of Barred Plymouth Rock chickens to determine the manner in which 

 the JMendelian factor, representing the barring pattern, operates physiologically. 



It was found that " all feather follicles are not capable of continually pro- 

 ducing successive feathers for an indefinite time. In the case of the general 

 body plumage a feather is usually not regenerated more than about three times. 

 The precise number of successive regenerations varies with different birds and 

 different feathers. Wing primaries seem to possess the maximum regenerative 

 capacity. After about the third removal in the case of body feathers the follicle 

 usually remains in a perfectly quiescent condition, taking no steps whatever 

 toward the regeneration of a new feather. 



"This failure to regenerate is, however, very definitely related to the natural 

 molt of the bird, and in the following way : A follicle which has been abso- 

 lutely inactive for a long period of time (e. g., six months) preceding the 

 natural autumn molt of the bird produces a new feather in connection with the 

 molt, in the same manner as does any other follicle of the body. In other words, 

 the process of natural molting reactivates the follicle which had been brought 

 into a quiescent state by successive feather removal. 



" The precise pattern exhibited by a particular feather is, in the usual course 

 of events, reproduced each time a feather is produced by that follicle with 

 extreme fidelity of detail. If, however, the feather is removed from the follicle 

 as soon as it is fullj;- grown, thus forcing continued regenerative activity of 

 the follicle, the pattern tends progressively to be broken up, and iirobably will 

 ultimately be entirely lost as a definite pattern. The experiments have not 

 yet gone far enough to enable us to speak positively on this latter point. A 

 progressive breaking up of an originally definite pattern is, however, very 

 clearly shown in a number of cases. The behavior of the color pattern in suc- 

 cessively regenerated feathers suggests, as a working hypothesis, that the 

 pattern factor or gene is possibly represented in each follicle by a strictly 

 limited amount of material, and that when this is used up the pattern is lost. 



" The secondary sexual feathers of the male, such as the saddle hangers, 

 only appear as adult i)lumage. The same follicles which bear these feathers 

 produce, as juvenile plumage, undifferentiated body feathers. The formation 

 of these secondary sexual feathers is not necessarily dependent upon any normal 



