CONTENTS. xxi 



CHAPTER XLVII. 



FURTHER STUDIES ON NUTRITION (concluded}. 



Nutrition of moulds, 608. Nutrition of parasitic fungi, 609. 

 Nutrition of the larger fungi, 610. Studies of mushrooms, 

 613. Form of the mushroom, 613. Fruiting surface of the 

 mushroom, 614. How the mushroom is formed, 615. Be- 

 ware of the poisonous mushrooms, 617. Wood-destroying 

 fungi, 619 page 322 



CHAPTER XLVIII. 



DIMORPHISM OF FERNS. 



Dimorphism in the leaves of ferns, 624. The sensitive fern, 

 625. Transformation of the fertile leaves of onoclea to 

 sterile ones, 626. The sporangia decrease as the fertile leaf 

 expands, 628. The ostrich fern, 629. Dimorphism in tropi- 

 cal ferns, 630 page 340 



CHAPTER XLIX. 



FORMATION OF EARLY SPRING FLOWERS. 



Trillium, 631. The adder tongue (erythronium), 633. Indian 



turnip, 634 page 347 



CHAPTER L. 



HETEROSPORY. POLLENATION. 



Origin of heterospory and the necessity for pollenation, 639. 

 Both kinds of sexual organisms on the same prothallium, 

 639. Cross fertilization in monoecious prothallia, 640. Ten- 

 dency toward dioecious prothallia, 641. The two kinds of 

 sexual organs on different prothallia, 642. Permanent sep- 

 aration of the sexes by different amounts of nutriment 

 supplied the spore, 643. Heterospory, 644. In the pterido- 

 phytes water serves as the medium for conveying the 

 sperm cell to the female organ ; 645. In the higher plants a 

 modification of the prothallium is necessary, 646. Pollena- 

 lion, 649. Self pollenation or close pollenation, 649. Wind 

 pollenation, 650 Pollenation by insects, 651. Pollenation 

 of the bluet, 653. Pollenation of the primrose, 654. Pol- 



