COITTENTS. 7 



Department Bulletin No. 1090. — The Effects of Inbreeding and 

 Crossbreeding on Guinea Pigs — Continued. 



II. Differentiation among inbred families: Page. 



Differentiation in color gy 



Abnormalities. 



38 



\ 



Differentiation in vigor ' " " ^2 



Detailed study of family characters '.........'. 45 



Records of five families in recent years ....'.' 55 



Summary " _" _' 57 



Appendix — Tables 7 to 15 '.'.'..'. 59 



Department Bulletin No. 1091. — Life History of the Kangaroo 

 Rat (Dipodomys spectabilis spectabilis Merriam): 



Importance of rodent groups i 



Investigational methods "_ _ _ 2 



Indentification ] 3 



Description 5 



General characters 5 



Color 6 



Oil gland 6 



Measurements and weights 7 



Occurernce.... 7 



General distribution 7 



Habitat 7 



Habits.. 9 



Evidence of presence 9 



Daily and seasonal activity 12 



Pugnacity and sociability 13 



Sense developments 14 



Movements and attitudes 15 



Storing habits 15 



Breeding habits 15 



Food and storage 18 



Burrow systems, or dens 28 



Commensals and enemies 33 



Commensals 33 



Natural checks 34 



Parasites 35 



Abundance 36 



Economic considerations 36 



Control 37 



Summary 38 



Bibliography 40 



Department Bulletin No. 1092. — Pedigreed Fiber Flax: 



Introduction 1 



Early selection work 4 



Elimination of poorer selections 6 



Comparing with the check by percentages _ 9 



Using the score card for the elimination of the poorer selections 10 



Improvement by cross-pollination ^^ 



Instruments devised for use in breeding flax 16 



Commercial test of pedigreed fiber flax strains 17 



Increasing the quantity of pedigreed seeds 19 



Seed increase by growing two crops a year 21 



Summary 21 



Bibliography 23 



Department Bulletin No. 1093.— The Gipsy Moth on Cranberry Bogs: 



Introduction ^ 



Artificial cranberry bogs ^ 



How bogs become infested with gipsy moths ^ 



Wind dispersion of gipsy-moth larvae , 



History ^ 



Selection of bog for experimental purposes ^ 



Observations on wind dispersion ^ 



Description of traps ^ 



Record of trap observations 



